The Kazakh language is the official language of Kazakhstan. Estimates of the numbers of speakers in that country vary from around 5 million (Ethnologue) to nearly 10 million (Peter K. Austin '1000 Languages: The worldwide history of living and lost tongues'). The difference may be attributable to the difficulty in classifying first-language speakers - many people in Kazkhstan are bi-lingual, speaking Russian as well as Kazakh.
We have put the worldwide number of speakers at around 9.5 million, in around 13 territories. Outside of Kazakhstan, the largest number of speakers are in China, Uzbekistan, Russia and Mongolia.