The two sides will make the short trip to Wembley Stadium on Sunday for a place in May's final.
Despite a recent 0-0 draw between the teams in the Premier League, Bale believes that Spurs have the extra quality to see them through this time around.
"Chelsea are a great side and have done really well in the Champions League. It won't be easy," he said. "But if we are on our game on the day, then we can reach the final because I feel we have the better team.
"We played very well at Stamford Bridge recently, it ended goalless but we had the better chances on the day and we probably should have won the game. That will give us plenty of confidence going into this match."
A victory for Harry Redknapp's side against their London rivals will see them reach their first FA Cup final since 1991.