If you paid the full amount with a gift card, your refund will be added back to your Amazon account as a gift card.
If the purchase price was higher than the gift card value and you made up the difference with an Amazon Barclaycard payment, you'll receive separate refunds. The gift card value will be added back to your Amazon account, and the card payment will be credited to your card account. Any rewards earned on the refunded amount will be taken off your rewards balance.