Yes, if you want to return items you paid for with a gift card online or in store, the money will be refunded to your voucher code so you can reuse it for your next order.
If you only paid for part of your order with your gift card and the rest was purchased with another payment method, the amount you purchased in combination with the Gift Card will be credited to your gift card code. The remainder will be refunded to you in the form of your previously selected payment method.