Boyd netted his 21st goal of the season as the Scottish champions restored their 10-point lead at the summit of the Clydesdale Bank Premier League with a 3-0 win over Hibernian.
But a yellow card late in the first half was a cause for concern as it was thought the caution had sent Boyd crashing through the disciplinary points barrier.
However, referee Steve Conroy clarified the booking, for a foul on Merouane Zemmama, was for obstruction, meaning he be available for the hugely-anticipated clash at Ibrox on February 28.
Smith said: "I looked at the list during the week and when he got booked I thought he might have been out. But the referee says it was for obstruction which is just a two-point one so he has a point to go yet.
"We are pleased to have him, there is no doubt about that. Kris Boyd and Kenny Miller are just coming back from injury and it's important they have a bit of continuity. That would mean Kris can play so we are pleased about that."
The Rangers boss added: "Everybody makes all these assumptions - it was 10 points and then it was eight points and, when it was eight points, we weren't going to win the league.
"We will just carry on and I think that's the sensible thing to do. People don't give enough credit to the other teams in Scotland and they think it's easy for the Old Firm to win games. It's not.
"We are delighted to have the 10-point gap but you know the consequences of not winning so nothing should be taken for granted and I don't think we would."