According to this one chart I found, it should take you 23-24 weeks or 575-600 hours of study. This is assuming a lot of things, such as willingness to learn the language and dedication to intensive study; and, it should be understood that this is just the average for English speakers and for individuals can pick it up faster or slower than this.
Each person learning abilities vary!
Depends. I want to learn it but need to learn Spanish first
Rather shorted than if their native language were Chinese or Georgian.
Much would depend on your general experience of learning other languages, and on the adaptability of your mind in understanding that every language "works" in a different way, also on how long you study every week,, and whether you have a good course.
the difficult thing is not the French but the French
In more cosmopolitan cities like Paris or Bordeaux I would learn much faster because there are also many people who speak English.
600 hours of class if you squeeze it into 24 weeks
Several years under normal circumstances
In Canada, the French language course taken by a great many people, especially in the government, and military is one year long. That makes people at least competent in French, and, it is a full time course.
It depends on several factors. For example, if the person has never the opportunity to use the language and interact with native speakers, I'd say they'll never become fluent in it. On the contrary, if you have to use it on a daily basis, you'll certainly learn it much faster. French is among the easiest languages to learn for an English speaker and there's a lot of free material available on the internet.
It also depends on the point at which you would be satisfied to say 'I've learned enough French'.
learning language well involves mimicry in speech a good ear for rhythm
breath control, a different verb noun article order,
memorization and practice
I have known automatons who ace tests,but cannot carry on simple conversation,some who know every little point of grammar syntax,vocabulary,and no matter how long or how old they get,still have 1st semester anglo/gringo accents,( a tenured chgo school system teacher)
practice is still necessary which I do regularly inside my widda head.
if you have chops for accents,,the rest is dog work,,consistent learning, it does take years.