The New Zealander said that form will be the main factor in determining who plays in the three test matches.
"The captaincy is a great honour, but whoever the captain is, there'll be no guarantee he plays," Gatland told the BBC.
"The captain's form has to be good enough. I think whoever that person is has to rise to that; the message is it's a great honour to captain the Lions but your form has to be good enough to be selected for the tests.
"When you are looking at a captain, you want to be reasonably confident he is going to be starting in the tests. But it is not a guarantee, it is just part of the criteria."
Gatland selected his then Welsh national captain Sam Warburton to lead the Lions to Australia in 2013, then chose lock Alun Wynn Jones to lead the side for the third test in Sydney when Warburton was injured.
While Warburton was replaced by Wyn Jones as captain of the national team before the Six Nations, Gatland said the loose forward could still be a contender for the Lions leadership role again.
"I think Sam has had a terrific Six Nations, he has played really well and I am really pleased for him," Gatland added.
"He's a different captain to some other players. He leads by example. He doesn't say a lot but he has had that experience.
"He's one of the guys potentially in contention, definitely. In my mind there's probably half a dozen people but we haven't really narrowed that down yet.
"The most important thing is to pick the squad first and then talk about the captain afterwards."
Warburton's biggest issue would be whether he could supplant compatriot Justin Tipuric or Ireland's Sean O'Brien as the first-choice openside flanker in a test side.
The 28-year-old played in the number six jersey in the Six Nations, though Ireland's CJ Stander and England's Maro Itoje are more traditional blindside flankers likely to provide greater physicality to the breakdown and better lineout options.
Other national captains in consideration would be hookers Rory Best of Ireland and England's Dylan Hartley, while Scotland scrumhalf Greig Laidlaw was ruled out for much of the Six Nations with an ankle injury.
(Reporting by Greg Stutchbury; Editing by Peter Rutherford)
Share
