https://www.aa.com/i18n/utility/FAQs...s/GiftCard.jsp
Q: How many American Airlines Gift Cards can be used during one transaction or purchase?
A: Up to eight (8) Gift Cards can be used per transaction. Note: Gift Cards may not be used for paper tickets
Q: Can multiple American Airlines Gift Cards be consolidated onto one Gift Card?
A: No. You may not consolidate your American Airlines Gift Cards onto one Gift Card.
Q: Can I receive a refund on travel purchased with an American Airlines Gift Card?
A: The terms are governed by the rules that apply to the specific fare you have purchased. If a refundable fare was purchased, the Gift Card amount will be refunded in the form of a voucher. Please contact Reservations for more information.
So you have 10x $100 gift cards, and want to buy a $1000 ticket. Could you buy 2 refundable tickets costing $500 each, refund them to vouchers, then use the 2 vouchers to buy your desired ticket?