Bruce has overlooked Akpom since the Championship leaders' defeat at Preston over Christmas.
And, according to the Tigers boss, the on-loan Arsenal striker "spat his dummy out last week".
But the 20-year-old returned into the starting line-up at League One Bury and responded with an early opener before sealing his first senior treble after the break.
The hosts claimed a late consolation but could not prevent the 2014 runners-up booking their place in the fifth round.
Bruce said: "I'm delighted for Chuba. He spat his dummy out last week and threw his toys out of the pram.
"He's a young player with lots of ability and I'm sure it'll do him the world of good. It's good to see him get a hat-trick and I'm sure he'll remember that for a while."
GETTY
Chuba Akpom bagged his first hat-trick against Bury
"I used the squad, like I always do, and if I can call on players like that then it bodes well."
On the game, Bruce added: It was difficult for us because of the conditions but I was pleased with the way we went about it.
"To be fair to Bury, they were spirited and aggressive, and they made it a proper cup tie. In the end we got the breaks and that little bit of quality saw us through."
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