Brady Tkachuk (St. Louis, Mo./Ottawa Senators) evened the score at 9:26 of the middle frame, ripping a wrister from the top of the left faceoff circle past the shoulder of Danish netminder Mads Sogaard after an offensive draw win by Eichel.
Eichel gave Team USA it first lead of the game 57 seconds later, snapping a shot home directly off a faceoff to give his team a 3-2 advantage.
Noah Hanifin (Norwood, Mass./Vegas Golden Knights) doubled the U.S. lead at 17:23, as he fired a quick shot after a block from a Danish defender that snuck through the five-hole of Sogaard.
Denmark drew within one with three seconds remaining in the period on a goal from Phillip Bruggisser.
Jake Guentzel (Woodbury, Minn./Tampa Bay Lightning) regained the two-goal U.S. advantage 7:24 into the third, blasting a one-timer home after a centering feed from Auston Matthews (Scottsdale, Ariz./Toronto Maple Leafs).
Team USA took a 6-3 lead at 14:27, as Jack Hughes (Canton, Mich./New Jersey Devils) banked the puck off the skate of Danish goalie Fredrik Dichow from behind the goal line into the net.
U.S. goaltender Jeremy Swayman (Anchorage, Alaska/Boston Bruins) earned his first Olympic victory, stopping 18 shots.
Team USA is back in action Sunday (Feb. 15) for its final preliminary round game against Germany. Puck drop at Milano Santagiulia Ice Hockey Arena is slated for 9:10 p.m. CET (3:10 p.m. ET) and the game will be broadcast on USA Network and streamed on Peacock.
NOTES: Team USA outshot Denmark, 47-21 … The U.S. went 0-1 on the power play while Denmark went 0-3.