It has been said that soon the content of the Easter eggs will be added into GTA 5 and this should start with the jetpack, which should make an arrival with the 1.13 update. This is only if you can believe a discovery from a hacker of course.
The hacker had been taking a look through some of the files in the game and found a folder that had the files for the jetpack. He them shared screenshots, which you can see here.
Since GTA 5 came out last year gamers have been waiting to see jetpack features, which have played a part in other GTA games. Right now they have been disappointed as there is no jetpack.
Now that the discovery of the files has been made, fans hopes have been reignited, however for now you should take things with a pinch of salt as the folder could be nothing more than a placeholder.