In the announcement of the seventh season, it was mentioned that the season finale of the sixth season hit a viewer record. I found this odd and checked with Wikipedia. It recorded 8.11 million viewers, which is larger than any earlier episode. In general, one can see that the series has gained more and more viewers as the series progresses.
This begs the question on how they are counting. This is a series where each episode is a natural continuation of the previous episode. To me this means that one would see the episodes in succession, starting at the first and then the second until one gets fed up with GoT. That would mean that more would have seen the earlier episodes than the later.
Or is that just me? Are other people starting to see GoT at the season finale? People that doesn't think it's worth seeing the episodes up to that.
AFAIK, HBO allows its subscribers to view all the episodes of GoT from the beginning - so people starting a subscription don't have to miss any episode, being able to watch it from the beginning if one wants to (without having to pay extra for it).