Q: If I redeem an iTunes gift card on iTunes can I still use it on the Mac App Store or just on iTunes?

Hello Stephanie,

Your iTunes gift card can be used in these online stores; iTunes Store, App Store, iBooks Store, and Mac App Store. For more information, take a look at the article below. Let me know if this works or if you are running into issues. 

iTunes Gift Cards

https://www.apple.com/itunes/gifts/

Regards,

-Norm G.