What I want to know is: Did I do a good job by using gambling to save him? Or do I just make him have an interest in gambling as a source of income?
I don't know what the title has to do with your story, but anyway, based on your story, you have achieved both. You saved him and you made him interested in gambling as a source of income because you did not mention that you discouraged him after you gave him money and you won. You should have told him that he should not do it again, putting money intended for his family to gamble.
We should discourage people from using money allocated for food for the table. As the head of the family, your obligation is to secure the family's basic need, which is food.
But if that person use gambling as a source of income, he will only regret because he can lose much money without he can imagine. Gambling is not a source of income so he doesn't need to thinks like that instead just use gambling to have fun. That will be better for him because he can playing gambling without thinks to make money and only fills his spare time by playing gambling.
If he is lucky and win the money, that will be a good for him because he can recover his lose before and make money from gambling. But that doesn't mean he can use gambling as a source of income and he needs to think to search for the other ways to make money. We must educate people not to use money for fills their daily needs to playing gambling because that can makes them lose that money and they will difficult to fills their daily needs.