It is not about physical immortality but about spiritual immortality and physical health and longevity.
Unless you are someone like Jesus Christ or other Avatars that incarnate in this world, who can literally materialize their thoughts instantly, and who can be true or purely fantastical...
The only way to verify anything is to test it yourself.
Qi is real.
Manipulating Qi through Yi Gong is real.
The real question is how much is possible, how much you can, or should, do with it...
Ultimately this is ancient psychosomatics.