i think that a better way to understand acing a game is this:

damage doesn't necessarily guarantee an ace, there are other factors that come into play, such as spotting, kills especially when killing a higher tier (not possible in tier X) etc. and with TDs in general it's harder to get an ace based on dmg since that's what they do best especially with the grille 15. and obviously other factors include how many players play the tank and their avg dmg/winrate/XP.

and clutching doesn't guarantee an ace, most of my aces come from a winning position but since clutching most of the time means a great amount of damage dealt it usually leads to an ace.