you mean it's not a quote at all?In movies, tv etc. the noun phrase "a has-been" means a person whose career "has been" great but "is not any more". They are still famous, but only for things they did in the past. Their career is "over".
"Lauren Bacall is a has-been. She hasn't made a new movie in 5 years".
Apparently someone made a statement like that about her publicly, and the movie star decided to invent a new term implying her career "will be" great again in the future. Putting it into the same format, that would make her a will-be".