They are currently 1st in the West at 41-20-6. And he's probably the biggest reason why.
With Eichel in lineup
34-15-5 (.676 p%) 173GF 139GA (+44 GD)
= 111 point pace over 82 games
Without Eichel in lineup
7-5-1 (.577 p%) 40GF 43GA (-3 GD)
= 95 point pace over 82 games
When he's in the lineup, Vegas plays like the best team in the West. Without him, their points percentage would put them 9th in the West.
Similarly, they've significantly outscored the opponent at 5v5 when he's on the ice. But without Eichel on the ice, their 5v5 goal differential would make them a bubble team:
With Eichel on the ice
46GF / 31GA +15 GD
Without Eichel on the ice
101GF / 100GA +1 GD
I'm fairly confident that the team is okay paying him $10M if it's the difference between home ice until the cup final and missing the playoffs.
What's impressive is that he's still having such a positive effect despite his injuries.
He had 13g 29p in his first 26gp before getting injured. Then he returned (probably prematurely) from a lower body injury and put up only 2g 5p -9 in the next 12gp, with only 2p in the 10gp leading up to the ASG. His skating and shooting seemed noticeably less explosive during this stretch.
Since the ASG break, he's got 8g 16p 16gp - the extra time off seemed to have helped him recover to closer to 100%.
So that's 21g 45p +27 in the 42gp where he's been "healthy" - which is a 41g 88p pace with a dominating goal differential. That'd be 11th in points per game among centers, just behind Matthews, Point, and RNH. And he's doing it while being his team's undisputed offensive leader, while those three guys are being outscored by their own teammates.
Ignoring his impact on Vegas's record and on ice results, $10M feels right for that caliber of player. He just needs to stay healthy.