Easy!
Escrow or middleman.
Buyer can use my codes and when he uses gift cards and receives items or deal is completed then escrow releases BTC to me.
That's not the concern, the concern is that you used illegitimately obtained credit cards (eg stolen) to buy the gift cards. They may then be cancelled/invalidated once you've sold them. (escrow or not will not prevent this from happening - unless escrow holds buyer's funds until the buyer spends all of the gift card value)