No, you would normally say "It has been a long time..." just like what you wrote after the word "mean."
"It has been a long time since he..." is common in everyday English.
The phrase
"He has been a long time waiting" is okay, but it is rare.
Instead,
"He has been a long time (long-time)..." is often used to describe a person's job, profession, advocation:
He has been a long-time writer...
She has been a long-time advocate of a clean environment...
Mark has been a long-time student of English...