Epistemic status: extremely rough model, please don't take too seriously, just trying to get ballpark estimates which someone might correct me on

It seems like there are a few considerations here:

1. Would this create a restaurant which would otherwise not exist, or a restaurant which would sell more meals than it otherwise would if it were in a different location?
2. If so, how many extra animals would be factory farmed?

For (i), if the rent you can get for a restaurant is higher than for a non-restaurant business then it seems like the market is implying the "best" (financial) use of the space is as a restaurant, suggesting the answer to (i) is at least in part yes.

For (ii), this suggests 12-15 sq ft per diner and assuming 70% of the area is dining space you get approx 300 diners at one time. Lets say 1000/day at capacity. If they eat more meat than they would at home (intuitively I guess they would but this is small, i can't find any source on this).

Lets imagine you get an extra 100 people/day eating out once from this decision, and they eat 25% more meat than they otherwise would. Then the average person in the US eats 100kg of meat a year or 270g/day. An extra 25% is about 60g or about 0.06 chickens, 0.001 pigs or  0.0003 cows (based on numbers I got from a quick google) so you get ~2100 extra chickens, ~11 extra cows or ~35 extra pigs  a year. If the restaurant is a chicken restaurant then this is clearly much more weighted towards chickens, and in fact if it causes people to eat chicken if they would've eaten beef at home, this is an underestimate. Let's use 2100 chickens for now.

There are not very precise estimates available for how effective animal interventions are, but this by Rethink Priorities in 2019 suggests corporate campaigns such as those by the Humane League saved 120 chickens per dollar from broiler cages (with extremely wide error bars). If subsequent campaigns are 10x less effective (I don't know what a good estimate is here but I'd guess future campaigns will be less effective than past ones as they hit diminishing returns) then you get 12 per dollar, or 2100 chickens with better quality of life for $175. If you think non caged lives are 10% better than caged lives this would be more like $1750 to offset the harm I estimate here.
 

Charles_Dillon had a really great answer and I think his numerical calculations seem right. I encourage you to round up any answer because of the uncertainty in any calculation.

Since your question is great and you care about impact for animals here's another way to have an impact:

By far, the food with most suffering is chicken and especially eggs that come from caged, egg laying chicken. 

What this means is that, calorie for calorie, or bite per bite, eggs and chicken can be ten or hundred times worse than other animal products.

E.g., see Peter Singer saying this:

So what this means is that, you can further increase your impact by ensuring your restaurant tenants only serve "cage-free" eggs, which now account for about 20% of the US supply. 

Even better is pasture raised eggs in a local farm is (but this is much rarer). 

This shouldn't be very hard to do, since it sounds like your space can attract hip restaurants, and the cost of these nicer eggs is low. 

Charles_Dillon had a great answer. 

Answering the question of "Where to donate" that you asked:

TLDR; Consider donating to the EA Animal Welfare Fund, because I think they are more able to fund nimbler, high-impact projects, and the fund is well advised and connected to the entire farm animal welfare movement. 

Explanation:

I think one reason to donate to the Animal Welfare Fund is that they are more able to support nimbler projects. For example, The Humane League is a great organization to donate to and has a great track record of success. Now, the funding landscape for farm animal welfare has some structure now, so an established organization such as the The Humane League and their important initiatives seem to get funding somewhat reliably. In contrast, it's still hard for smaller projects to get started. The Animal Welfare Fund can make this happen.

Secondly, the job of the EA Animal Welfare Fund is to find and donate to good causes. They exist to serve you and use your donation money well. They grant to the Humane League and others. Their fund managers are extremely experienced, respected and aggressive in maximizing impact. Based on this, it seems to make sense to delegate granting to such an organization.

It would be quite surprising to me if your idea did not work out, simply because doing good for animals via donations tends to be really low cost (but might depend on what "a lot more money" really means in your case). Imagining for instance that for each and every restaurant in the world some non-negligible cut of the rent (say 5%) would go into effective animal charity, my super rough 3 minute Fermi estimate says that would amount to something in the order of $10 billion per year. Given that about 80 billion land animals are slaughtered each year, that would mean that at a cost effectiveness of sparing 8 animal lives per dollar donated (which doesn't sound entirely unrealistic), your suggested approach to leasing to restaurants would, on a global scale, not only be net positive, but very theoretically end factory farming of land animals (obviously not in practice given diminishing marginal returns). It's a very hypothetical argument, but maybe it adds something.

Apart from that, maybe there's a way to attract more vegetarian/vegan restaurants in particular? No idea about the concrete processes and legislature around that, but maybe you have some power in that regard.

I am assuming that in the not leasing to restaurants case, these businesses would not find additional central locations (so would not operate) and that those who would otherwise dine in these central restaurants would purchase meals from less central locations or non-restaurant stores. These alternative meals would use more animal products (presumed for at home cooking and as a competitive strategy of restaurants that cannot market a central location).

In the leasing to restaurants scenario, assuming excess demand in the non-restaurant case, the price would fall with an increased supply. This could motivate those who would have otherwise bought less central or non-restaurant meals to purchase the central meals with less animal products. This indicates that leasing to a restaurant would benefit animal welfare.

This reasoning does not consider the leverage that a central restaurant can have. For example, if this is a very cool and affordable vegan place, then it can motivate other competitors to introduce vegan options. Similarly, if this is a horrible steakhouse that exhibits animal suffering and workers’ poor standards, then other meat restaurants could suffer a reputational loss and plant-based restaurants could increase their market share. So, if it is possible to select renters, then some cool healthy vegan restaurant chain, which uses marketing to retain customers.

I am further assuming that 100% of non-restaurant tenants would operate from other locations and that this would not affect their operations or profit.