Is it permissible to pay off a debt owed to relatives first, or to pay off a bank loan with interest, knowing that the debt to relatives is years old?

Borrowing with usury without an urgent necessity is a major sin, and one must repent from it. If it is possible to repay usurious debts by disposing of some non-essential properties while also repaying relatives' debts, then that must be done. If that is not possible, then one should prioritize repaying relatives' debts and turn to Allah in repentance from dealing with usury, and supplicate frequently.