Transmission life will depend on several factors, the first being your driving style. If you baby it, of course it will last longer. But if you do a lot more spirited driving with hard launches and acceleration, that will shorten the life.
Towing heavy loads is another major factor that can shorten the life of the transmission. A truck that regularly tows a 6,000 lb boat to the lake every weekend is going to have a LOT more wear and tear than a truck that doesn't tow anything.
Regular transmission fluid changes is yet another factor. If you go over 100k miles without changing the fluid, that's not going to be particularly good for a transmission.
And the number one killer of transmissions is HEAT. If the fluid regularly gets overheated (such as from towing) then that will dramatically shorten the lifespan.
I got just barely over 100k miles out of my 4L60E. I bought my truck at 52k, immediately had the fluid changed. I changed it again at 75 or 80k miles. Then the trans shit the bed at just over 100k miles. But the transmission shop who rebuilt my transmission said it wasn't actually the clutches that wore out. The sun-shell gear broke, and that's what destroyed the transmission. He said if the sunshell has not failed, who knows how many more miles and years I could have gotten out of it.