If you want to quit from gambling you have to quit completely. If you still feel like gambling, you can not stop gambling. You have to do it totally, if you do it halfway, you'll just spin in a loop without stopping. Do your best or not at all.
He can still stop gambling if he feels like to gamble. There are too many ways to gamble without using your own money, there are play money that he can try or download some gambling apps that requires him no money to gamble.