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.
All gamblers are surely aware that they can gamble for free but obviously they just have greed in their mind so they start gambling with real money , when they do so it's no more for fun so when they lose they deserve it for being greedy