Provided that the gift or pre-paid card is registered and activated, and belongs to one of our payment vendors (Visa, MasterCard, American Express, Paysafe Card, Webmoney, GiroPay, iDEAL, or Paypal), there should be no problem using a gift card to pay for a game account for The Elder Scrolls Online.
Just make sure that the card meets the following requirements:
The card has been activated.
The card has been registered with a billing address.
The card has enough money on it to cover the total cost of the transaction.