The pronunciation of the acronym GIF depends on what website you go onto. For example, if you go into the world of Tumblr, its pronounced 'jif' whereas if you where to go into the land of Facebook, many people pronounce it as 'gif' as in 'gift' without the 't'.

The creators of the format pronounced GIF as "Jif" with a soft "G” as in "gin". Steve Wilhite* says that the intended pronunciation is meant to echo the American peanut butter brand, Jif, and CompuServe employees would often say "Choosy developers choose GIF", spoofing this brand's television commercials

*Steve Wilhite of CompuServe was the engineering lead on the team that adapted the GIF file format





sources
http://www.i-mockery.com/minimocks/clash-of-the-titans/5.gif