Do you mean a Disney Gift Card? Yes you can use Disney Gift Cards on a
Disney cruise ship. The ship currency is US Dollars. This does not change even though the ship changes location. Its the same in Europe. I use a Disney Gift which I load with US Dollars when I am in
Disneyland California and I use it when I am on the ship in Europe. I just go to Guest Service and tell them I want to add money to my onboard account. You have to tell them a specific amount eg 100 US Dollars. If you don't spend the whole amount of the money by the end of the cruise, you have to go to Guest Services and then will put whatever money you did not spend back onto the Disney Gift Card. Your onboard account has to be at 0 in order for you to leave the ship.