As I see it, gifted writers are those with that "something extra" in the way they write. Their words are memorable; their stories or illustrations stay with us. When we read, the rhythm of their prose carries us along and we're hardly aware of the writing.
By contrast, haven't all of us read books and articles that were laborious and wooden? We might even ask ourselves, Why am I reading this? Lack of ability has never stopped people. Some less-than-good writers get by with excellent plotting or interesting characters.
We also have to allow for taste. I rarely read literary fiction, even though my friends tell me some of those authors are highly talented. When I was a pastor, our organist believed nothing of true beauty had ever been written after the baroque period.
You are the only one to whom the answer is important. If you recognize you're gifted, your continued improvement shows your giftedness. If others comment on your improvement that may be a hint of your having talent.
Along that line, I had to take a series of tests before I could enter graduate school and I scored quite well. "Am I really smart?" I asked the man who scored the test. "Or is it that I work hard?"
He laughed. "If you weren't smart, it wouldn't have mattered how hard you worked."
Apply that to writing. If there is no ability, you won't improve. You won't learn. And I've had a few students like that. No matter how much I tried to help, they couldn't understand what was wrong with their prose.
If I can improve my writing (and do so)
that implies some level of giftedness.