The jetpack was recently confirmed to be in the next Fortnite update in the in-game menu. Unfortunately, it appears as if the jetpack will be a limited time item, to go with the LTM Shotguns.

Jetpack Update Fortnite Battle Royale

Still, I cannot wait to try out the jetpack! Stay tuned to see the full update release notes for the jetpack update in Fortnite Battle Royale.