As an idea it sounds appealing.
In reality to have a humanoid that would cost millions and it isn't even that reliable yet so instead of buying a humanoid you can pay salary to a good chunk for people years so now you say which one you prefer if you want to build a successful one and I mean in terms of profit making,
The cost of maintaining and acquiring it will indeed be higher than the cost of filling that casino with competent employees that will serve the people well, and you as the employer will still have some left-over money, not to mention how those robots might malfunction at times due to a lack of servicing or a system breakdown.
To me, it's completely insane to leave an entire physical casino to be handled and controlled by robots; if they must be present, there are areas where few of them can be invested, and they will work perfectly in that area with the assistance of human actors.