It gonna depend of your imbuements (Critical or not), weapons (What crossbow) and lowblow rune (Use or not).
With every hit you deal 20% of more damage.
If you hit 10 times of 100 of damage each one (1000 of damage) with the extra 20% of Elemental Damage you make at the end 1200 of damage.
Using Soulpiercer (Best croswbow) you got critical extra damage +10% and critical hit chance +10%
Using Low Blow you got critical hit chance +8%
Using Powerful Strike you got critical hit chance +10% and critical extra damage +50%
Total critical hit chance +28% (Let's put it on 30%)
Total critical extra damage +60%
If you do the same 10 hit of 100 of damage each one (1000 damage), 3 of this hits gonna be critical damage with 60% of extra damage (180) you make at the end 180 of damage.