Gambhir smashed three huge sixes and five boundaries in his quick-fire fifty.
Gambhir and Brendon McCullum started Kolkata innings aggressively as they scored 50 for no loss in the six mandatory powerplay overs.
Earlier, Chennai skipper MS Dhoni won the toss and decided to field against Kolkata on Monday.
The hosts Kolkata have made three changes in the playing XI for the match as Brendon McCullum and Marchant de Lange are included in place of Shakib Al Hasan and Brett Lee. Among Indian players Laxmipathy Balaji included in place of Manvinder Bisla.
Whereas, visitors Chennai make one change in the side as they included Faf du Plessis in place of Albie Morkel.
Known for their last minute scrambles, the Super Kings need to win their remaining two matches to assure themselves of a berth in the last-four and their captain Dhoni has a reputation of coming up with the best in pressure cooker situations.
On the other hand, a win for the Knight Riders would hand them the pole position and a guaranteed place in the play-offs.
Chennai’s nine-wicket thrashing of leaders Delhi Daredevils on Saturday could not have come at a better time, as the Knight Riders were given a wake-up call by a Rohit Sharma-inspired Mumbai Indians in the afternoon match of the same day.
After their humiliating 27-run loss at home, the Knight Riders would find themselves down while the Super Kings would look to avenge their five-wicket defeat in the first leg of the tournament.
Kolkata Knight Riders: Gautam Gambhir (capt.), Jacques Kallis, Manoj Tiwary, Yusuf Pathan, Debabrata Das, Laxmi Ratan Shukla, Rajat Bhatia, Sunil Narine, Marchant de Lange, Laxmipathy Balaji, Brendon McCullum (wk).
Chennai Super Kings: Mahendra Singh Dhoni (capt./wk), Michael Hussey, Murali Vijay, Suresh Raina, Ravindra Jadeja, Srikkanth Anirudha, Dwayne Bravo, Ravichandran Ashwin, Ben Hilfenhaus, Shadab Jakati, Francois du Plessis.