Priestland has struggled to recapture the performance levels that saw him produce headline-grabbing displays during last season's successful World Cup and RBS 6 Nations campaigns.
The Scarlets number 10 started Wales' opening autumn Test defeat against Argentina earlier this month and then appeared as a substitute for more than half the game against Samoa five days ago (Wales lost 26-19) after Dan Biggar was injured.
But despite ineffective displays in both encounters, Gatland has named Priestland in a starting XV
showing five changes for Saturday's Millennium Stadium clash with world champions New Zealand.
"He had a great World Cup and Six Nations last season and when he plays well, the team does," Gatland said. "He has taken the brunt of a lot of the criticism in the last two weeks.
"I do not care who you are, if you can handle it you will come through the better for it, and I have told him that. He has not experienced it before and we have to support him.
"We could have made a change there (fly-half), but there are certain players we need to support and back. Biggar is carrying an injury and James Hook is not available next week (against Australia).
"We are well aware of the pressures Rhys has been under, but his confidence and form will come back.
"One of the things that attracted us to him was the confidence he displayed and even a slight cockiness you look for. They (fly-halves) need that to control the game and the people around them.
"We see an incredibly talented player who is just not playing quite as well as he can at the moment, and we back him."
Scarlets midfield powerhouse Jonathan Davies has recovered from a groin problem to make his first appearance of the autumn series on Saturday, replacing Ashley Beck, while hooker Matthew Rees returns to the front row.
Elsewhere, lock Luke Charteris is in for Ian Evans, who has taken only a limited part in training due to knee trouble, and openside flanker and captain Sam Warburton replaces Justin Tipuric.
"I expect a response from the players," Gatland added. "We want a performance everyone can be proud of.
"We are going to go out there and, I hope, throw something a little bit different at the All Blacks and put them under a bit of pressure.
"You have to be different and take a few risks against them, which is what we will do."
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