Is it permissible to give usurious money extracted from the bank to relatives (such as brothers who are not dependents) to pay off their debts or fulfill their needs?

It is not permissible to keep money in an interest-based bank. The principal should be withdrawn from it. As for the interest (usurious gains), it must be disposed of by spending it on public welfare, charitable causes, and on those in need whose upkeep is not obligatory upon you, such as relatives to pay off their debts or fulfill their permissible needs.