This is the sad reality that this game will have very little impact on womens hockey overall. Really, they couldn't have picked a worse olympics to win gold from the "have an impact on the sport" perspective. The game didn't finish until about 2am eastern, and was shown on NBCSN, that alone severely limits the potential of eyeballs.
The good news: NBC says the game was the most watched late night broadcast in NBCSN History, so it had at least 2 million viewers (Best I can find, the previous record for NBCSN was an NHL playoff game that had 1.9M viewers). That also means for the second consecutive olympics, the Womens Gold Medal game will almost certainly be the most watched hockey game of the Olympics in the US, outperforming any mens game.
The bad news: That will still be less than half of the nearly 5 million people who watched the womens gold medal game in Sochi - which was show in the middle of the afternoon on NBC's main channel.
Of course, the exposure and publicity from the win can only help fuel the continued growth of the sport, but realistically, there just weren't enough people watching for this one game to have been a significant turning point moment that causes any major boost in interest outside of the Olympics.