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Gatland, on a sabbatical from Wales to lead the British and Irish Lions tour to New Zealand, will be at Friday's penultimate game against Ireland.
After two defeats, Edwards says Wales' players will want to make amends.
"They've got two games left and they can prove a point," ex-Wales and Lions scrum-half Edwards said
"That should be another incentive for the Welsh players to prove a point to Warren Gatland that some of the previous results they've had really don't matter.
"They might, just about might, surprise Ireland."
Rob Howley's side travel to France for their final game of the Championship on Saturday, 18 March.
Fourth-placed Wales, who are out of title contention after back-to-back defeats by England and Scotland, have named an unchanged side for the game at the Principality Stadium.
Edwards believes Friday's game sees the two top contenders going head to head for the number nine jersey he famously wore in the victorious tour of New Zealand in 1971.
"Conor Murray and Rhys Webb are vying for the Lions position," Edwards told S4C's Y Clwb Rygbi.
"Although there are others in the market there is no doubt this will be a real tough encounter.
"I'm expecting Rhys Webb to really show his capability but I've got great respect for both of them. It will be very interesting to see who comes out on top."
Ireland can set up a title decider with England in Dublin on 18 March with victory in Cardiff and Edwards is expecting a tough match for Howley's unchanged side.
"Whenever you play Ireland you know what you're going to get," Edwards added.
"It might not be fine skills; it will be all about heart and who wants it more than anybody else.
"I'm expecting nothing different from the Irish and I'm looking forward to it immensely."
Watch the full interview with Sir Gareth Edwards on S4C's Y Clwb Rygbi ahead of this Friday's game between Wales and Ireland from 19.15 GMT.
Wales' players can prove a major point to Lions coach Warren Gatland in the final two Six Nations games, says Sir Gareth Edwards.