I went looking for it, and apparently you’re right. He said “Jif”. He’s either trolling or being obstinate. People don’t see it that way, especially seeing as it’s the hard “G” from “Graphical” in the initialism. So he’s applying a pronunciation rule of soft G when followed with “i” when used in a word to an initialism - and acronyms aren’t words (noted: they can become treated as such).
GIF is not a word. So soft “g” when followed by “i” does not apply.
E: corrected to initialism, and now we have to debate if an initialism pronounced as an acronym should obey the soft G rule, or if it should be an exception. Exceptions do exist, so the soft G is not a hard rule.