Can a single stab to the gut with a knife really kill a person in a minute or less, like we often see in the movies? (Heck, can a single stab to the gut kill a person at all?)
There are several points in the gut where a knife could cut into or sever major blood vessels or blood rich organs and cause you to bleed out in seconds.
Certainly; without modern antibiotics it was a near guaranteed death sentence from infection, even if anything immediately vital was missed.
The major arteries are somewhat protected by the guts and spine. But still fully knifeable. The vessels that feed the liver seem particularly vunerable.
Need answer fast? 
Apparently needed answer faster.
When using a stiletto or other narrow implement, standard practice is several rapid jabs to maximize the chances of hitting something vital. If using an edged blade, the most effective tactic is to stab and then swing the blade left and right to sever as much as possible.
It built the Roman Empire, according to Vegetius.
Maybe not the abdomen per se, but a single thrust upwards at 45 degrees to the solar plexus will result in death almost immediately.
Wouldn’t peritonitis be pretty much guaranteed?
How long before that progresses past curable?
It would seem the infection of pretty much everything in the abdomen and thorax would set in real quick.
And what happened to old-fashioned insert-twist-and-remove? You and your fancy new-fangled blades too good for evisceration?
The OP asked about dying in less than a minute. Modern medical care, with antibiotics and abdominal surgery, will generally mean that peritonitis will not occur, or will be manageable. Open him up, suture the holes, wash and replace the organs, and close up. Prophylactic antibiotics and the prognosis is usually good. IANAD.
All three parts of insert, twist, and remove, require considerable strength. Try it on a beef or pork roast (that you don’t care much about). You need quite a sharp knife and some skill and strength to penetrate deeply, and even more strength to twist the blade about and chop things up inside. Consider also the likelihood of the muscles contracting upon penetration, and it is quite common to require two hands to pull the knife out.
Instant or near-instant death needs to cut the abdominal aorta, or a deep enough stab wound to the heart. Both require that the attacker grip and use his knife properly and get past the ribs, which will generally not happen with the wild downward stab the untrained person often uses.
Regards,
Shodan
I think this is related to my “In the movies you can choke someone to death in a minute.” thread. Answer was movie goers don’t want to see someone taking minutes to die realistically.
I somewhere got the impression that a knife blade needed to be about 5" long and inserted just below the rib cage with an upward thrust into the heart for a good, quick kill.
But back to peritonitis: if there is no medical care and the digestive system (esp. if the digestive system) is nicked, the digestive bacteria would be lethal within a few minutes - true or am I lucky I never needed to rely on that bit of “info”?
My very favorite movie stab death - bad guy sits in seat behind victim in theater and uses this bizarre switchblade which extends the blade straight out of the grip, through the seat back, through the spine/thoracic section of rib cage, causing, of course, instant, silent, death (wouldn’t want to disturb the rest of the folks in the theater).
Peritonitis takes much longer than a few minutes to kill. Hours, at the least, and more likely days.