How many people speak Cantonese in China?

Cantonese is perhaps the strongest of China’s numerous regional dialects, and it’s so distinct it’s seen by some linguists as virtually a language in its own right. All Chinese television and radio broadcasts are supposed to be in the national language Mandarin, but an exception has long been made in the southern province of Guangdong — home to most of the estimated 70 million Cantonese speakers. Now the authorities say that from March all prime time programmes will have to be in Mandarin. When the changes were first proposed last year, hundreds of people took to the streets to defend their local culture.
                                                                VOA 2011-12-27