This is a hand where 4C is definitely Gerber (there aren't many) because there is no better use of 4C

Once North shows 2 Aces South knows all they need to know to bid 6C.

6C makes because you have time to set up the SJ as your twelfth trick. Cash SA, over to CA, play SK and ruff a Spade, draw trumps, over to DA, cash SJ, low Diamond towards the Queen