Question

I have always doubts about the use of il and ce to express a neutre pronoun.

Example: C'est vrai que tu parles bien Français / Il est vrai que tu parles bien français

Answer 1

"C'est vrai." is a complete sentence, meaning "That's true.".
"Il est vrai." as an ended sentence is very, very formal and old-fashioned.

"Il est vrai que je suis riche." means "It is true that I am rich.".
"C'est vrai que je suis riche." means the same thing but is more colloquial