Met Life to GCT is not an issue for me, though I had no idea there was an elevator in the vicinity. My issue is getting, quickly and easily, without going blocks out of the way or having a heart attack, from the east end of the GC Station shuttle platform up to the GCT terminal on the main level to be able to go through GCT and, perhaps, to the escalators to the Met Life building (obviously without climbing stairs). Now you keep telling us about the new elevator(s) in 1V. You've not mentioned much, at least that I've seen, about where and how in specifics that could help one, for instance, plan their route. At last check, neither had MTA - even their staff doesn't seem to know about this, or if they've heard of it, thought it was a year or two in the future. Yet they've just spent a fortune on the shuttles to make them ADA accessible without, as far as I can tell, adding elevators or escalators at the east end of the GCS shuttle platform up / down for GCT main level access. And when I ask them, they don't know. So it's great that you know that 1V has a solution. What exactly it is and whether it actually works for affected commuters in a hurry I've no idea.
You really want me to say all this again?
There are 2 options from the shuttle platform:
Option 1) Exit into One Vanderbilt (the exit is to the left of shuttle track 4). Take the elevator up one level to the mezzanine and then go through the doors to the right into GCT.
Option 2) Use the passageway from the shuttle the 4,5,6,7 trains. Exit from the subway (bear left just past the escalators to the 7 train). Once you exit from the subway the elevator will be to the left of the escalators/stairs to GCT (it will be where all the MetroCard machines are). That elevator goes up to GCT just inside GCT where E42nd St and Park Av is .
I can't make it any clearer than that.