The legendary midfielder appointed as Under-23s manager last week but on Saturday found himself fast-tracked into the top job following Maurizio Sarri's sacking.
Sarri lasted just one year with Juventus, paying the price for their shock Champions League exit to Lyon, with Pirlo penning a two-year deal to succeed him.
Gattuso, now manager at Napoli, said of his former Italy and AC Milan team-mate: "Well he's screwed now. That's the job.
"He's lucky to be starting at Juventus, but this profession is one where a great playing career is not enough. You have to study, to work hard, and you don't get much sleep."
Gattuso's first steps into management came at Swiss side Sion in 2013 before roles with Palermo, OFI Crete, Pisa and Milan.
Like Pirlo, Gattuso was initially appointed at Milan's youth team coach before being promoted following Vincenzo Montella's sacking later that year.
"Being a player and being a coach is really not the same thing at all," Gattuso added.
"It's a totally different profession and we can't learn it just from books, we need to get in there and work hard. It's a different world."