Hi
Perrine !!!
I did't see that movie and I don't know who she is, sorry.
Tonia seems only an Italian nickname for
Antonia. I much prefer
Antonietta in this case (it is my grandmother's name) and I would be glad to use it on a daughter.
As Russian/English name I strongly dislike
Tanya. This is because it is too similar to 'tenia' (taenia the parasite worm). I hate this name because of the desease.
Tonya is much much better.
It is more similar to
Antonia and has a strong, mature feeling in it.
Clearly I pronounce
Tanya as TA-nya and
Tonya as TO-nya XD
After that I would say that I pronounce both
Antonia and
Tonia with a wide 'o' (so TO) but
Antonietta with a more close 'o' so ('AW' -> an-taw-NYET-ta).
These pronounciations change based on the region but also depends on the person.