I've switched back and forth between hard-'g' and soft-'g'. The original team who developed the gif standard preferred the soft-'g', So now I'm inclined to give them the benefit of the doubt. Although to my ears, both are fine choices. Whatever floats your boat. I'll personally tailor my pronunciation depending on the present audience.
https://en.wikipedia.org/wiki/Pronunciation_of_GIF
In a similar vein, I've also switched up the pronunciation of the prefix "giga-." For example, "Gigawatt," I'll sometimes pronounce it "Jigawatt," with a soft-'g'.