You may have more luck since it’s not a Disney restaurant. Don’t they take the Landry’s card, too? You could also call directly to try to get a reservation.Rainforest Cafe
It is not guaranteed, but we have been able to do it at several restaurants. We have a family member that lives near WDW and she can't always commit to a certain time because of work so she has shown up last minute before and they have always been accommodating. You may have to wait past your ressie time.