The midfielder has missed the last two games after he suffered a head injury in the opening day league draw at Aberdeen.
Having sat out the first- leg 3-1 win over Maribor as well as the league triumph over St Mirren on doctor’s orders, Gerrard is confident Jack will return for the clash in Slovenia tomorrow.
The Ibrox manager said: “Ryan is back in full training, so assuming he gets through today and tomorrow he will be available for selection.
“It could be a huge boost because he is in great form and he has played a very important role for us so far.
“When you are going away from home and you have a slight advantage, you want to put people in your team who will help you get a positive result and Ryan comes into that bracket.”
Former midfielder Gerrard said he was “jealous” of the way Jack dictated the engine room in the previous round’s win over Osijek and he wants the Scotland cap in his usual berth at Maribor’s 12,700-capacity ground.
Gerrard is confident Scott Arfield will also be fit to start tomorrow night. The 29-year-old sat out Sunday’s 2-0 league victory over St Mirren at Ibrox.
Gerrard said: “Scott was rested at the weekend. He had two or three weeks out with his knee and then came back and played two full games. One of them was with 10 men against Aberdeen.
“We had to protect him at the weekend so the idea was just to rest him. He had a little bit of a small issue but nothing major. Thankfully we got a win and actually rested him, which is good.”
Another midfielder, Lassana Coulibaly, was given a few days off regular training to rest his aching limbs.
The Mali international hobbled out of the game against St Mirren, but Gerrard revealed it was tiredness rather than injury which had overcome the player.
He told Rangers TV: “Lassana has recovered quite well and we don’t think it is a big issue, it is maybe more down to fatigue.
“He has posted some very big numbers in the last couple of games, in terms of distances and high speed, so I think it is just is body letting him know that he might need a little bit of a break at some point.
“It is a big game Thursday and we will have to wait and see what he is like in the next 48 hours before we make a decision on him.”