This was revealed on SteamDB.
The average audience of Artifact was reducing from the very release of the game. The game set new anti-records every month. At the beginning of January, the online was less than 2,000 people. Now the worst number is 957 people. Taking the fact that this project is Valve's child into account, this statistics is very bad for the game, putting it mildly. There are many games in Steam and their online exceeds Artifact's number.
The average online of the Valve CCG users is equal to ~2,200 people. Now, during the night-time, the number of players drops to 1,000 and less.
The fact that on 24 January Richard Garfield and several other workers left the team of developers proves an unavoidable failure of the project.