Gif is pronounced yiff2018-07-08 17:13:04
Fun fact, the source of this debate comes from English borrowed words. You see, while words borrowed from Old Norse kept their hard Gs, words from Old French had a sound shift where the G would soften in front of front vowels (ee, e, and i). Interestingly, Old English words with G underwent a sound shift where the Gs became Ys, so, since GIF is an English-made word, the correct pronunciation is "yiff"