I can loan him in one condition he needs to be sober and stop gambling for at least a month to show that he is not using the money for gambling and it will be under close monitoring and supervision.
Its hard to grant a loan to anyone who is deep into gambling even if you are close to him or you owe him something, lending him will just give him money and reason to continue gambling in the hope that they can get all their losses back.
This is actually a smart idea, but are you always going to be there to monitor him? As someone that has other things to attend to I don't think you'd have that time to look over someone's shoulders especially when we are talking about an adult here. It's possible that the moment you take your attention from him for a few days or probably even hours he might relapse and pretend like nothing happened
It is not a reliable idea of strategy, actually. It does not matter of close you are to a family member one will always are separate daily routines from one another, there are infinity of opportunities for that person to break the conditions of the agreement and continue to gamble with that loan.
It would better not to give money to such person at all, in my opinion, but to provide means of survival, like food, pay the rent for them, so the person who is addicted to gambling does not actually touches the money in anyway possible.
One must not underestimate the power and the urge of addiction those people feel and to the extent they are willing to go in order to continue to gamble. So it is better for both the lender and the borrower to do it that way.
Whatever, to each their own. I am not just capable enough to trust so much someone who is addicted to anything.