first, never believe hollywood or tv. It depends on several factors,:
1) what type of shot shell is used. Bird shot at any sort of distance over about 30-35 yards is going to pepper the person, but unless it hits an eye, or possible the temple area, it is easily survived. Using buck shot within a short distance can cause horrendous wounds, and at the right distacne could remove a limb.
2) what "choke" is in the barrel will determine how tight the shot stays together and for what distance, the tighter the choke, the more shot will hit a smaller area causing more damage.
3) what length barrel. A shorter barrel will spread the shot faster than a longer barrel.
My partner was shot with a 12 gage shotgun with an illegal 12" barrel, loaded with #7 bird shot at a distance of about 2 1/2 feet. He was wearing a heavy leather jacket. The resulting wound was very large, but not as deep as you would expect. He spent 4 weeks in the hospital and walked out under his own power. I saw a robbery suspect shot with #4 buckshot at 45 yards from an 18 1/2" barreled Remington 870. Only one pellet struck him, luckily it hit him in his "privates" and he decided he should really give up after all. I also saw a man commit suicide at point blank range with a hunting shotgun loaded with #7 1/2 bird shot. He placed it under his chin and pulled the trigger with his big toe, He literally exploded his head.
So you see, there are many many variables you have to take into consideration when answering your question.
shoot safe