The frontman leads the Championship scoring charts alongside Huddersfield's James Vaughan with five goals in four games.
Recent reports have linked Newcastle United with a move for the 25-year-old, but Hornets boss Zola is confident that he will remain at Vicarage Road.
"This is something the club is dealing with," BBC Sport quotes the Italian as saying. "I wouldn't be surprised because he's doing very well.
"I am confident he can stay with us and help us achieve what we want to achieve."
Watford's next match is a second-round League Cup tie at home to Bournemouth tomorrow evening.