Gift cards cannot be used as collateral because the lender will need to redeem the gift card in order to check its value (and to prevent someone else from redeeming it).
You have 48 negative feedbacks and you're telling me? Lmao
Gift card is indeed not a valid collateral as QS mentioned.
A valid collateral should be irreversible and the lender doesn't need to trust the person taking out the loan to not spend the collateral. With a gift card code you can spend the gift card as soon as you receive the bitcoins.
I suggest you try go to digital goods and sell your gift card instead.