I will advice him to stop gambling. I will not help him at all than to buy only food for him and it will not be expensive ones but cheap ones. He should stop the addiction and start a better life. It is as simple as that.
This isn't a bad idea and considering the fact that you are willing to help makes you a good person. But from experience doing all of these things might not tackle the situation, even after giving advice there are lots of gamblers that would still continue gambling. They might promise to make a change but it's going to be all pretence because their focus hasn't changed. Changing an adducted gambler isn't easy