It depends on some other facts as well like where are you, how is your society, and many more. Gambling is a common thing in some societies where almost every adult gamble and they do not forbid their grown-up children to gamble. If you talk about my society, he did two offenses at the same time. Stealing is bad regardless of where are you from. But, some parents tolerate it when their kids gamble.
If you talk about my society, gambling, and stealing, both are forbidden and punishable offenses. Gambling is not allowed at all. Let's say I didn't tell my son anything about gambling, but if he gets caught gambling, he will be punished I won't be able to help him. so, it is my responsbility to guide him no matter how.
As a parent then no one would really be happy if your children would really be ending up on stealing on you just because they do love or really that playing on gambling.Of course
you would really be having that kind of disciplinary action. This isnt something that good to be done and should really be stopped and controlled as much as possible.
This is where your parenting rights and authority would be shown.