Is it? Really depends what you want there. If the only thing you're looking for is gambling, that's pretty trivial to add, even for me. Do you mean to say you want it as an expansion to your brothel? Do you mean a place in town with characters or some kind of event to progress?
It might be a big ask if you want a casino in town that has not just "click to lose money and maybe gain more" but actually has
mini games.
Could be a big ask if you want a big win in gambling to get you a shot at winning a slave after you're gambled your way into VIP stuff, and have the slave their own specific character rather than generic whore.
Could be a big ask if you want gambling debt to result in them coming to your house to rape your girlfriend. That event basically exists anyway though, since your debtors do kidnap Alice to rape her anyway, and also come over to your brothel to rape her again later, while the leader of the thugs remarks "wow you just like watching your girlfriend get raped, huh. Kinda hot, we should fuck too"
I think that dev was getting kinda tired and lazy at that point.
But I'm rambling. What are you actually asking for?