Based on the information at my disposal, large casinos in Las Vegas generate the most revenues. Don't forget that casinos also reap their revenues from sales if hotels services, food and by providing other entertainment services. We should not also leave out the Internet betting on casino games which are gaining popularity now.
I have no idea but I can certainly do Google search and find out the answer. In my home country all the casinos are owned by the same company, there is no second companny that runs a casino. There is a monopoly.