Yes, you can use an (now commonly referred to as an App Store & iTunes or Apple Gift Card ) to pay for iCloud storage . When you redeem the card, the funds are added to your Apple Account balance , which Apple uses as the primary payment method for subscriptions like iCloud+ before charging any other method on file. How to use your card for iCloud storage:
How iTunes Gift Cards Work for Apple Music, iCloud & App Store can i buy icloud storage with itunes card