If you forbid something to a kid then kid will find that even more attractive. Forbidding anything will have contra effects in most situations.
I believe people hear many bad stories about gambling generally, sometimes with family members involved, that's always makes situation more complicated.
I'm not affected by any of this stories because I started to gamble with sports betting with friends from soccer, more seriously gambling came after. I build my way alone, and I know how to handle with gambling. Its something you need to learn. When we are about that its important for very life aspect you can think off, you need to know how to handle with good and bad times, and to not let something to lead you in crash or disaster of any kind. Gambling is special because you can climb fast, but you can fall even faster, don't fool yourself its like that in everything just time for climbing and falling is different.
Learn kids how to control their emotions and how to properly decide what is good and what is bad, if you try with forbidding kids will try to find a way to skip your bans and to try that sweet forbidden things.