Naming is probably one of the few language areas that I think should be prescriptive, even while language at large is descriptive.
A file format is not a sentient being. The creator's intent matters much more. If GIF had sentience and could voice a desire one way or the other, the whole discussion would be moot as it would clearly be disrespectful to intentionally mispronounce the name.
The G in gif is for graphics. Not 'giraffics'. And most people in the world have no idea what Jif even is, much less a particular catchphrase from an old ad campaign that barely even connects.
English has both pronunciations for "gi" based on origin. Giraffe, giant, ginger, etc from Latin; gift, give, (and presumably others) from Germanic roots.
Using the preferred one is just a matter of politeness.
Also, it's quite ironic to prescribe "linguistic prescriptivism" as wrong.