Legally? 

Hard to say, but you have to realize that the show does REALLY well on repeat showings.  I would say 4 million first showing and 5 million for repeat showings.  This may seem low, but given HBO is a premium channel that is great, especially with head on competition with Walking Dead.

The show is a huge success and proof is they keep renweing it even though it is so expensive to make at 60-80 million dollars a season.

Well the season 2 finale was watched 4.3 million people. So I guess it is safe to say the season 3 premiere was watched by at least 2.8 million viewers. But we gotta wait a few more days for the actual figures

Official numbers

"Thrones delivered 4.4 million viewers for its premiere at 9 p.m. and racked up 6.7 million viewers for the evening after its two repeats were tallied. That’s up 13 percent from its premiere last year."

http://insidetv.ew.com/2013/04/01/game-of-thrones-premiere-ratings-3/

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Even better than I hoped.

It has largely to do with how many people have access to a given channel.  AMC is on cable, HBO is a premium channel meaning far more people have AMC than HBO.  It is why generic shows on network television (NBC, CBS, etc.) bring in higher ratings, almost anyone who has a television can watch it.

HBO has their own criteria, and like I said given how expensive it is to produce they have to be making money hand over fist to so quickly renew and market it the way they do.

One last thing: it's called 'game of thrones' not 'the game of thrones'

Watched it. Loved it. Can't wait for more.

However, I do wish they'd stick to larger breasted women when shirts do come off. Just my preference and doesn't relate to storyline at all.

As for the story so far... yeah still going great.

I liked the whore bounding scene. 

But now that you mention it there where naked women in this episode

Finally it's that time of the year already haha. Another ten episodes of Game of Thrones.

Pretty good premiere... yeah it did felt a bit like episode eleven of season two in some scenes but I guess that was to be expected considering there isn't a huge change of pace from CoK to SoS.

Game of Thrones renewed for season 4

http://www.ign.com/articles/2013/04/02/game-of-thrones-renewed-for-season-4

meh, no belwas :( but it seems they can keep the high standard with season 3.