Luke here from the Shopify support team.
It's not currently possible to use a gift card as a payment method when creating orders manually through the admin. This is definitely a great idea that I can see other merchants benefiting from as well, so I'm going to pass this along to our development team as a feature request.
What I might suggest as an alternative for the time being is when creating an order in drafts and marking it as paid, include a note in the order that this was considered "paid" with a gift card, and then you can always disable the gift card in the admin if the funds are fully used. You also have the option of creating the order the same way a customer would through the checkout, including their information and using the gift card normally through the checkout but this would just send them an order confirmation instead of an invoice.
I hope this helps and I'll definitely pass this feedback along to our team. You can always reach out to our support team through our support page if you have questions!
I second that - I need to use this functionality for updating the balance of a shopify gift card that has been used physically in store via my POS system (Vend). Currently no integration exists between the two platforms with gift cards so I need a way to update a gift card's balance on one platform when it is redeemed on the other.
I THIRD this!!! - a system to integrate Shopify's online gift cards with Vend which allows a customer to present a Shopify online gift card instore to pay for products. You might say, "use the online checkout system and redeem the gift card through the online store", however not every product that is in Vend and in the physical store is available online so this theory doesn't work. Any ideas?