The Americans' win in front of 4,758 fans at MTS Centre put the defending world champions in the final against the winner of Monday's game between Canada and Finland. The U.S. has four points with a regulation win and a shootout loss and can finish no lower than second in the championship round.
The only thing the Americans have to do now is wait to find out who they'll play. Canada has two points with a shootout win and would be eliminated if Finland earns three points with a regulation win Monday.
"Every time we step on the ice it's preparation," said Gunn, a 27-year-old California native who's playing in her third world championship.
"We've probably been preparing since the Olympics for these games. I think we're ready."
U.S. head coach Mark Johnson said he hasn't yet decided if Gunn or Jessie Vetter will get the start.
Vetter, 21, was in net Saturday when the Canada defeated the U.S. 5-4 in a shootout.
Canada and the U.S. have met in all nine world championship finals. The Americans' only gold was a 1-0 shootout win in 2005.
There was no world championship last year because of the Olympic Games in Italy, where Canada won gold over Sweden. The U.S. lost to Sweden in a semifinal shootout and settled for bronze with a victory over Finland.
U.S. forward Natalie Darwitz said the Olympic letdown doesn't weigh on the players, especially because half of them are new and so is the head coach.
"What happened in the past, it's kind of over and done with," said Darwitz, who scored Sunday's first goal.
"This is a whole new team. It's still in the back of our heads, but we don't want to dwell on it. That's not our motivation right now."
The Americans peppered Finland goalie Noora Raty with 37 shots.
Captain Krissy Wendell, defenceman Molly Engstrom and forward Kristin King got the other goals.
Johnson admitted his team got off to a slow start against the Finns, largely because they'd just played Canada in such an up-tempo game the night before.
"It's challenging, it's hard, so the players were able to do what we needed to win the hockey game," Johnson said.
"This group has earned the right to play Tuesday night for a gold medal."
In looking ahead to Monday's game against Canada, Finland head coach Hannu Saintula knows his young players are in tough.
"We have to think that that game is a great challenge for us," Saintula said, adding a couple of his players are injured.
"We have to also think very positive. If we do some things very well, then we have to be happy. We try to win that game, but we have to understand it's not so easy."
He noted his players have to learn how to pass better and take shots when they have the opportunity.
Finland had a two-man advantage for 1:02 early in the second period, but couldn't even get a shot on Gunn.
Wendell, who also assisted on Darwitz's goal, leads the U.S. in scoring with four goals and 11 points.
Canadian veteran Hayley Wickenheiser is the tournament's leading scorer with 12 points, including six goals.