Since I downloaded my first GIF off a BBS in the late 1980s, I've pronounced GIF with a hard "g" like "gift." It looked natural to me, and like many others, it was an on-screen acronym that I didn't hear out loud until years later. I stuck with that pronunciation for years, even after I knew the "official" pronunciation.
But I'm not entirely comfortable disregarding the wishes of Steve Wilhite or the culture of animated GIF art, so I started taking a new approach last year:
To honor Wilhite's pioneering work, I pronounce every static or non-looping GIF with a soft-G. Every discussion of the file format, transparency, interlacing, and static GIFs are "jifs." These are all "jifs." So are these.
But the animated GIF, as we know it, was created by Netscape and popularized by the Internet, so I pronounce it with a hard-G.