Yes, multiple gift cards and/or store credits can used on the one orders.
Once you've added your desired items to the cart, click on the "Checkout" button (please keep in mind that gift cards can't be applied when using the "View Bag" option).
On the checkout page, you'll see a section labelled "Discount Code, Gift Card." Enter the first gift card code and click "Apply." If you have more than one gift card, just enter and apply them one at a time—input the next code and click "Apply" again for each additional card.