The two clubs have been in discussions throughout the summer, and reportedly agreed a £14m fee last month.
The negotiations have since come to a standstill, but the Uruguayan coach is confident of landing the Italian.
"I've got a good feeling about Fabio, but until it is done, it's impossible to comment," he told BT Sport.
Meanwhile Poyet also revealed that he wants Conor Wickham to stay at the Stadium of Light, amid interest from West Ham United.
"I want him to stay and that was the message all the time. That is the side as managers that we don't like," he added.
"We like to buy but when teams come in for your players you want to keep, we don't like that. We just want to be away from the bottom [this season]. We want to show that we are getting better."
Sunderland begin their Premier League campaign with a visit to West Bromwich Albion on Saturday.