You may say that if you are well protected and aware that you are about to be shot , and the strike is to the center of the chest with thick ballistic plates absorbing the shock then you can more than likely keep your balance. But saying a person can not be knocked down by a bullet impact, under quite a few real world conditions when they are taken completely by suprise, would not be strictly true.
I'm done arguing semantics with you amigo, peace!
Know the status of your weapon
Keep your muzzle oriented so that no one will be hurt if the firearm discharges
Keep your finger off the trigger until you have an adequate sight picture
Maintain situational awareness