Can I use a store bought Apple gift card to add to my Apple Cash app?

I purchased a gift card to add to my Apple Cash but I didn’t have it set up. I placed it on my iTunes but when I want to transfer to my Apple Cash which I set up afterwards I don’t know if I can do that. I’m trying to make an online purchase that requires Apple Pay but it shows no funds. Would like to know if an Apple gift card can be used for the Apple Cash app?