How do I check to see if a gift card still has value?
I just want to check to see if gift card has balance
You can always use the link at the bottom of the previously linked Support Article in case Apple Support may be able to determine the value of your Gift Cards:
"Contact Apple Support
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...or you can gift the cards with the caveat (truth) that you don't know precisely if they have previously been redeemed, but you will provide replacements if they have been redeemed.