managing a complex business such as a casino is very demanding and requires specific skills. and certainly not just for one man. as a developer, you may have done the most complicated part of the job, but that is only a small part.
first of all, you should first declare yourself about his vision of the whole business in the future, do you have the money to fund it all etc...
Probably you need first to find someone as an advisor, whom you would make a long-term strategy. after that, it should be clearer what kind of associate profile are you looking for. of course, keep in mind that if you start without start-up capital, everything will be much harder, with slightly poorer quality.