I don't think using Emacs can improve one's programming skills, I don't think some famous people used Emacs before can provide something, either. But these famous people encouraged me to learn Emacs when I wanted to give it up. Here I created a list of famous Emacs users.

Most people in this list are not famous because they developed Emacs, but they are famous and also use Emacs.

Joe Armstrong -- Erlang's author

In The Setup, Joe mentioned that

I write books using XML markup in emacs (nxml mode) and I write code in Emacs

Amelia Andersdotter -- Politician

In an interview, Amelia mentioned

but I do still use Emacs and org-mode

Steve Brust -- Author of Wad Taltos

In My Own Kind of Freedom, Steve mentioned

the book was written in emacs on a box running Mandrake Linux

Vernor Vinge -- Author of True Names and A Fire Upon the Deep

In an interview, Vernor introduced his work environment, obviously he was using Emacs.

Whitfield Diffie -- Security expert, Diffie-Hellman key exchange

On Hacker News, jf said

Whitfield Diffie is also an Emacs user. I once sat behind him at an awards ceremony and was able to observe him hacking on Emacs lisp during the event.

Marc Andreessen -- Mosaic browser autho, Netscape founder

Here is Marc's profile on EmacsWiki

Richard Gabriel -- Author of Worse is Better

Gabriel is initiator of Lucid Emacs.

Guy Steele -- Author of C: A Reference Manual

Steele is one of the authors of Emacs.

Peter Norvig -- Artificial Intelligence expert. Author of Design of Computer Programs

In an interview, Norvig mentioned

I dislike all three major OS – Windows, Mac, Linux. I like Python and Lisp. Emacs

Jamie Zawinski -- Mozilla and XEmacs main contributor.

Daniel Weinreb --Founder of Symbolics

Daniel Weinred was a pioneer of Lisp and Emacs

Julian Assange -- WikiLeaks founder

A code snippet authored by Julian Assange.

Mark Zuckerberg -- Faceook founder

In the movie The Social Network, Mark used Emacs to edit PHP and Perl scripts. He also mentioned in his blog

it’s definitely necessary to break out emacs and modify that perl script

Guido van Rossum -- Author of Python

In an article about Python user experience, Guido mentioned

I am mostly an entrenched Emacs user

Linus Torvalds-- Linux kernel and Git author

In an article on Google+, Linus mentioned he was using emacs as his main editor.

Donald Knuth --Author of TeX and The Art of Computer Programming

There is one Elisp code snippet on Donald's homepage: color-mode.el

Richard Stallman --GNU Emacs author.