Yes, it does sound natural and it is correct....only English should be written with a BIG letter (English) and not english.

Yes, it is grammatically correct. You need to ask, "DOES this sound natural?" (Or, IS this a natural way to say it?) I would not recommend asking, Is this natural? as we often use that when asking about very strange habits! Ha! For example, "My friend likes to sleep upside down hanging from a tree like a bat. Is this natural?" So that why I'd either ask, DOES this sound natural? Or, IS this a natural way of saying it. And as the other person says - don't forget the CAPITAL E. English. And Portuguese for your language. Capitals! All languages and countries deserve capitals!

It is the exact way, word for word, I would say it myself. Variations, all meaning almost exactly the same thing, would include: "I've been studying English since 2014." "I have studied English since 2014." "I've studied English since 2014." Is there a difference between "I have been studying English since 2014" and "I have studied English since 2014?" If you ask, people will strain to find an answer of some kind, but I don't think there is any difference. Is one of them better or more natural than the other three? I don't think so. How do native speakers decide between "equally good" ways of phrasing things? I don't know, it is a great mystery.

You can even say. i have been pursuing to learn english since 2014.

Yes.