Is it permissible to accept a bank's invitation to an Iftar banquet?

If the bank is usurious, then eating there falls under the ruling of dealing with commingled wealth, and the opinions of scholars on this matter have varied between prohibiting it and disliking it. It is forbidden to attend a banquet if it is prepared to promote a usurious transaction, or to inaugurate a branch, or for similar forbidden purposes, due to the attendance constituting assistance in wrongdoing and encouragement of it.