A couple of years ago I wrote this comment below an answer:
On mainland China 他 is used for both male and female. I've only seen 她 used as a stylistic thing for advertising and some old formal writing.
Since I wrote that comment I have had a few people ask about whether or not this is true. When I think about it today I am not sure what my original thinking was and I am doubting myself over whether or not this is a true statement.
I haven't been back to China in 3 years (going in September, yay!) and I haven't picked up a newspaper in a while. What I do recall is seeing 她 used in social media (微信 posts) which has only become mainstream in the past few years.
Here is what Wikipedia says on the subject:
In 1917, the Old Chinese graph tā (她, from nǚ 女, "woman") was borrowed into the written language to specifically represent "she" by Liu Bannong. As a result, the old character tā (他), which previously also meant "she" in written texts, is sometimes restricted to meaning "he" only. In contrast to most Chinese characters coined to represent specifically male concepts, the character tā is formed with the ungendered character for person rén (人), rather than the character for male nán (男)."
So how correct is my original statement and has social media and the internet caused an increase in the use of 她?