That's not from a lack of sleep. If you want to build strength and muscle, do less aerobic exercise and eat more - a lot more. You need to be in a caloric surplus for a while.
Given that sleep provides you with HGH, sleep definitely has a massive effect on strength and muscle (of course, a caloric surplus is also necessary).
Nope, GP post is correct. Your body dramatically increases muscle synthesis and nervous system improvements while you’re asleep. A caloric surplus is one piece of three-part puzzle: progressive overload, caloric surplus, and sleep.