He said he had also changed his earlier view that coming out of a tough pool as the Australians had was an advantage in being "battle-hardened" for the business end of the tournament.
"I'm not sure that's the case any more," he said in explaining the All Blacks' freshness was now a big advantage.
"The amount of injuries we (Wales) picked up, and how battered our players were, and Australia and South Africa were pretty battered as well coming out of some pretty tough games. The All Blacks have had an easier run. They had a tough game against Argentina first-up, but had a pretty easy quarter final where they played extremely well, and a tough game last week and finished stronger than South Africa the last 10 to 15 minutes, kept their patience and didn't panic when they were behind.
"I think potentially there is a bit more in the tank for the All Blacks and that might make the difference."
Gatland felt the freshness factor and the All Blacks' desire to see the final test for Richie McCaw, Dan Carter, Ma'a Nonu, Conrad Smith and Keven Mealamu tilted the scales in New Zealand's favour.
"You can't underestimate the emotion that will bring for that group of players and for the youngsters...but they've also got to keep that emotion in check, and make sure it's controlled emotion."
Gatland said he was interested in leading the Lions tour to New Zealand in two years but described the match schedule as "crazy" and added he "it probably wouldn't bother me" if he was passed over for other candidates such as fellow Kiwis Joe Schmidt and Vern Cotter whose Irish and Scottish national teams also reached the World Cup quarter finals along with Wales.
"Whoever agreed to that schedule from the Lions' point of view, it's crazy," he said. "I don't see how you could even win that. You're playing five Super Rugby sides, New Zealand Maori and three tests, all in a five-week period. It's so tough.
"Having been involved in South Africa (in 2009 as an assistant coach) and leading the Lions in 2013, it's a great experience, and if you get offered the opportunity, it's probably something you can't turn down. But if I didn't get the chance, looking at how tough it is, it probably wouldn't bother me."
Gatland also confirmed he wants to return to New Zealand to coach once his current contract with Wales ends after the 2019 World Cup in Japan.
"The plan for me is definitely to come home for a period. If I'm involved in provincial rugby or Super Rugby that would be great, but if not I might have to go to the beach for six to 12 months and put the feet up.
"That's the plan. I would have been away long enough for now. I'm only 52 and hopefully I've got plenty more years coaching."