Different theatres can wok differently, but here's the general breakdown in North America.
1) Theatres get a small percentage of a film's gross. The percentage can also change week to week. These are all very political deals and they involve what screens a film will be on and other such intricacies. Usually a theatre keeps somewhere close to 70 or 75% of first and second week gross. But sometimes it is much lower. Paramount has famously demanded their take to be up to 90% on some films in first week. Sweeney Todd is an example. Either way, even if the percentage of gross for a theatre goes up incrementally each week the gross of a film usually goes in a downward trend so they are still getting less money.
2) Bigger chains often have mote control over their snack bars, but they will often use other companies, as my theatre does, to essentially run product. In our case we use a company out of San Francisco called Pacific Concession. I don't know the details of the arrangement but my understanding is that it's somewhat split 50/50. The way I've heard it, bigger chains like AMC or Cineplex get more straight to their pockets to cover their own costs (more like 75%, though I may be wrong.)
3) From what I understand the Studios essentially cover cost of distribution, but i do believe there is a set fee to lease a print in both first and second run. That fee is apparently relatively negligible though.
What I'm saying my not be entirely correct, and it is likely not true for all theatres, but it should give you an idea of income. Keep in mind that operation costs or nothing to sneeze at for a movie theatre. There is a reason ticket prices are so high: theatres need to make money to survive and grow, and they need to raise prices to keep the profits from drowning under operation costs and studio pricing politics.
If Keith wants to add or correct I welcome him.