The October Steam numbers were quite strange (strong gains for 750 Ti, 1050 and 1050 Ti), they are back to a normal trend in November... probably the Chinese internet café problem again.
No big shifts otherwise, RTX GPUs haven't shown yet in the stats, Radeon RX 590 neither.
GTX Kepler - Pascal is still around 60% of the Steam hardware base (GTX Pascal still around 40% on its own), similar Radeon GPUs still between 7% and 8%... the other 33% only allow light gaming (GeForce GT + MX GPUs, Intel + Radeon APUs, DX9 GPUs...).
I'm quite conservative with the number of total active Steam accounts... since SteamSpy got castrated half a year ago, we have no indications whatsoever, so I'll leave them at 300 million accounts for now, even if they are probably higher.
Based on 300 million accounts and 96% of them with Windows, the estimate for systems which are faster than a PS4/XBO are still around 160 - 170 million Windows Steam accounts:
I also took a look at the "Vulkan system" statistic, but their numbers don't add up. Counting together the percentages the sum is way over 100%: