Here is a link to an EY paper that covers this topic and gives the IRS cite. Looks like the IRS is taking a tough stance that would agree with this banks application. The IRS seems to feel that because a gift certificate/card has a readily ascertainable value it must be taxed, whether or not it can be converted to cash.
Here is the IRS guidance. Frankly, the EY paper is more helpful because it discusses some IRS interpretations.
"Consult with your tax advisor!"