Source wikipedia: By June 2010, Martin had finished four chapters for The Winds of Winter from the viewpoints of Sansa Stark, Arya Stark, and Arianne Martell.[4 chapters] In July 2010, he added an Aeron Greyjoy chapter that had been moved from A Dance with Dragons to The Winds of Winter, accumulating around 100 completed manuscript pages.[5 chapters] Following the publication of A Dance with Dragons in the summer of 2011, Martin announced his return to writing the series in January 2012. In December 2011, Martin posted a The Winds of Winter chapter from the viewpoint of Theon Greyjoy.[6 chapters] He also announced that another sample chapter would be included at the end of the North-American paperback version of A Dance with Dragons,[not including this chapter as it still is yet to be released] expected to be released on October 29, 2013. (International paperback editions of A Dance with Dragons published a year earlier did not include a new, as yet unpublished sample chapter.) In the first quarter of 2012, Martin read new chapters of other characters at public events, including the chapters of Victarion Greyjoy and Tyrion Lannister.[considering these were only 1 chapter each, it makes a total of 8 chapters till now] Martin published another sample chapter from Arianne Martell's POV on his website in January 2013. [9 chapters]
By June 2010, Martin had finished four chapters for The Winds of Winter from the viewpoints of Sansa Stark, Arya Stark, and Arianne Martell.[4 chapters] In July 2010, he added an Aeron Greyjoy chapter that had been moved from A Dance with Dragons to The Winds of Winter, accumulating around 100 completed manuscript pages.[5 chapters] Following the publication of A Dance with Dragons in the summer of 2011, Martin announced his return to writing the series in January 2012.
In December 2011, Martin posted a The Winds of Winter chapter from the viewpoint of Theon Greyjoy.[6 chapters] He also announced that another sample chapter would be included at the end of the North-American paperback version of A Dance with Dragons,[not including this chapter as it still is yet to be released] expected to be released on October 29, 2013. (International paperback editions of A Dance with Dragons published a year earlier did not include a new, as yet unpublished sample chapter.) In the first quarter of 2012, Martin read new chapters of other characters at public events, including the chapters of Victarion Greyjoy and Tyrion Lannister.[considering these were only 1 chapter each, it makes a total of 8 chapters till now] Martin published another sample chapter from Arianne Martell's POV on his website in January 2013. [9 chapters]