The guy has one chance.
Inherent stability of the aircraft, so it must be taken advantage of.
Take a paper plane that has been folded and trimmed correctly and it will glide to the ground, without any control inputs on the way down. The paper plane does not know if it is in IMC.
This incident happened in France in the early '70's. VFR on top and was going to remain on top until his fuel ran out. Didn't have a real clue where he was and was low on fuel but the only real thing he did right was to call for help. I believe ATC got a pilot or instructor in and talked him down. This is what they told him to do:
1/Carb ht on, Power, 1500 rpm and leave.
2/ Feet off the rudders and leave them off!! (Tie them under the seat if necessary.)
3/ No aileron inputs. I.E., keep the wheel horizontal.
4/ Elevator to set up Vg and trim.
Did I say feet off the rudders?
This works as I have tried it. If you doubt it, experiment yourself or take a safety pilot with you and try it under the hood. All you really need is the ASI. and it is better to have no control inputs, than the wrong inputs.
No one seems to teach this for some reason these days but I am sure there are pilots that would be alive today if they used the above escape.