The Gers number one was replaced by Wes Foderingham for the 4-0 Ladbrokes Premiership win over Ross County on Wednesday night after picking up a knock.
Rangers boss Gerrard said: "He is improving. He will do a light session today and we will see how he reacts to that, but there certainly has been an improvement in the last 48 hours.
"He is better than 50-50 at the moment so we hope in the coming days that he continues to improve but he has a good chance."
'Surprise over Levein sacking'
Gerrard admitted some surprise at the timing of Hearts' decision on Thursday afternoon to sack manager Craig Levein.
The Edinburgh club announced Levein would not return to his previous position as director of football and had stepped down from the board, although he will stay on in a lesser role until the end of the season.
Assistant manager Austin MacPhee will take charge for Sunday.
The former Liverpool and England captain said: "I'm probably surprised, a little bit, at the timing, on the eve of a semi-final.
"But I think if you look at Hearts' form it is probably not as much a surprise. I never like to see other managers lose their job so I certainly feel for Craig.
"But he is still around in the background so I am sure he will have an input somewhere along the line."