He unquestionably does have a gear to pull away and has shown it on numerous occasions throughout his career at BSU. Whether we should take him or not is a completely different debate, but the dude is incredibly talented.
Jeanty has already shown he can pull away from legit defenses. He did so with ease against Oregon this year.
Last year against Washington (National Championship runner up) he took this catch for a 50 yard touchdown outrunning their defense
The beauty of modern day analytics is we can easily gauge how fast a player like Jeanty is on the field. He has legit speed.