It is understandable that computer users who encounter this acronym for the first time might well assume that since the “G” stands for “graphic,” gif
should similarly be pronounced with an initial hard g, as in go
However, the inventor of the format, Steve Wilhite, has insisted from its introduction at a computer conference in the late 1980s that the pronunciation is /dʒɪf/ [jif] Show IPA
with an initial soft g, as in gelatin
That pronunciation is even part of the official specifications for the format and is the one used by many computer gurus, but both pronunciations are commonly in use.