Is the 1% ratio, which is returned to the customer from the value of purchases made via Visa and Mastercard and which the bank describes as a "gift," considered usury (riba), and is the father sinful for not withdrawing his money from this bank?

If you have dealt with an usurious bank and taken money from reward and gift cards, then you must withdraw your money from this bank immediately and cease dealing with it except in the most restricted circumstances. If the father deals with these banks or forbidden credit cards, then you must advise and admonish him, and remind him that what he is doing is a great sin if the truth becomes clear to him and he does not respond to it.