The Wales winger is having a superb season and, on Friday, he was nominated for both the PFA Player of the Year and PFA Young Player of the Year Awards by the Professional Footballers' Association.
However, the 23-year-old has been on the sidelines for the last two matches, having turned his ankle towards the end of the Europa League quarter-final first leg against FC Basel.
But he has made a fast recovery and Villas-Boas said on Friday: "Gazza has been training for the last two days with the team and on his own since the beginning of the week.
"He has made good progress from the beginning of the week to training with the team, so definitely will be up for selection."
Asked if Bale would start the match, the manager added: "This is a decision I have to make.
"We recognise the impact he has had for us. With the run that he is on it can have that factor.
"It is good having key players around and players who have been decisive, especially in this last part of the season is always inspirational for everyone. It's good to have him back."
Jermain Defoe and Aaron Lennon have also been sidelined of late but both could be involved on Sunday.
"All of them are in with a chance of making selection," added Villas-Boas, who has seen his team lose ground in the race for a UEFA Champions League place, having won just one of their last four Premier League games.