1. As for Mattie's third wish, Oprah Winfrey asked Mattie to appear on her show.

2. About Mattie's third wish, Oprah Winfrey asked Mattie to appear on her show.

3. Concerning Mattie's third wish, Oprah Winfrey asked Mattie to appear on her show.

4. Regarding Mattie's third wish, Oprah Winfrey asked Mattie to appear on her show.
--------------------
Are they all the same in meaning? What are the similar words to 'as for'?

All mean the same thing, yes.

http://www.thesaurus.com/browse/as%20for?s=t

Yes, all four sentences have the same meaning and convey the same information. The similar words to 'as for' in this context are 'about', 'concerning', and 'regarding'. These words are used to introduce a topic or subject that is being discussed. In this case, they are used to introduce the topic of Mattie's third wish and Oprah Winfrey's involvement in it. While the specific word choice may vary, the overall meaning remains the same.