Recent months for the Steam Hardware Survey have indicated losses for Linux and for September showed the Linux usage of the Steam Linux client at just about 1%.
In looking at the just-released October 2013 survey details, there isn't much difference. When it comes to Linux operating systems, Ubuntu 13.04 64-bit is in the lead at 0.37% followed by Ubuntu 12.04.3 LTS 64-bit at 0.19%, Ubuntu 13.10 64-bit already at 0.15%, Linux Mint 15 at 0.12%, Linux 64-bit at 0.1%, Ubuntu 13.04 at 0.1%, etc. At the end of the day, there hasn't been too much change out of Steam Linux usage over the past month.
The October 2013 survey results are available via SteamPowered.com. Next week also celebrates one year since the Steam Linux client debuted in closed beta form.