It all depends on the brand! Some only allow one gift card to be used per transaction, others allow more. You can find more info for the brand you're looking at by adding a card to your cart and then clicking the picture of the card in the cart. Here you'll see any restrictions on how they can be redeemed.
If you're shopping on the Raise app, you can see this same info by tapping on any of the listings under a brand and adding it to your cart. You'll see more details on how a card is delivered and how it can be used as well as the brand's terms there.