At This Point, What He Needs the Most is not Money But Help.
Because he is gambling with money that he does not have, this sibling is in an extremely critical situation and needs assistance as soon as possible. He anticipates that his sister will come to his aid and pay off his gambling debts by taking money out of her savings account. He is counting on her to save him.
This sibling is in dire need of assistance right away since he is gambling with money that he does not possess. If he has any sense at all, his brother will give him some space first, and then send him to treatment so that he can give up drinking soon.