Can a B-movie movie get promoted due to high rating from audience?

The term "B movie", at least in modern movies, doesn't have any kind of official meaning. It's not a rating that gets applied to a movie by some organization, it's really just a "genre" of movie.

Originally, the term B-movie was used in much the same way as the B-side of a musical single record; the "B" movie was the "other half" of a double feature. The B movie was use as the lead in -- the same place we currently see trailers, for example -- and rarely got much promotion of its own. These days, double features are pretty rare, so the term almost never has this meaning.

Instead, it's typically used as a reflection on the budget the movie has. A B movie is a low-budget movie that is not an "art" film. The term isn't always meant as an insult -- sometimes B movies become very well known for taking risks or breaking movie conventions that high budget films would never dare. Just because a B movie becomes popular doesn't change the fact that it was filmed on a low budget, with all of the associated stylistic choices that come with it.

So no, there's not really any way for a B movie to "become" an A movie, any more than an action movie can "become" a horror; it's just a way to describe the way the movie was made.

I assume you are talking about B-movies. If I am wrong please let me know.

"B" movies were:

"...films that were made cheaply and quickly. They were used to fill the bottom half of a double bill when double features were standard." -History of Narrative Film, (Cook-third edition)

Tarantino and Rodriguez have done some movies (such as Grindhouse) in the last few decades that are basically an homage to the "genre", but they are generally considered too well-connected and/or monied to be in the same class with Corman. Another example would be Asylum's Transmorphers, a so-called mockbuster.

Nowadays, about the closest thing we have to B-movies are fan-films created with a Nikon D5 (or similar) and posted on YouTube.

So, the B is due to billing, budget, and often, but not always, quality.