All English is based on etymology which is why it’s such a hard language to learn. Looking at how a word is spelled always takes second place to where it comes from.
GIF was pronounced with soft g since it came out, back in the 80s/90s when it was shared on AOL and CompuServe. Year, decades, later it came back into social media with Reddit and Twitter, and people pronounced it based on what it looked like it would sound like, which is most similar to hard g like gift.
That doesn’t mean GIF never had a soft g. It just shows how old you are or when you discovered it when you use the hard g.
https://www.olsenhome.com/gif/compuserve-big.jpg
Since it was announced in 1987, if they mentioned the pronunciation it was soft G. The inventor and CompuServe would tell you it was soft G. CompuServe’s applications would tell you if soft G in their docs.
It’s even in the documentation of PNG which came out 7 years later that says soft G is correct in GIF, and they wanted people to pronounce PNG as “ping”, not “pinj”. (Yes, really)
See https://www.olsenhome.com/gif/ for more examples.