According to an interview for a French gaming news outlet, Nobuo has said that he is not involved with the VII remake.
Nobuo Uematsu's involvement with the series has off and on again since going independent and forming his own music company SMILE back in the early 00s. Since then he has composed mainly ballad style songs a few compositions for the mainline series. His last full work on a Final Fantasy was for Final Fantasy XIV. He also did the composition for Final Fantasy VII: Advent Children.
In the years since going independent, Uematsu has lend his talents as a composer to other studios and musical artists like Mistwalker, Emiko Shiratori, and RIKKI.
It will be interesting to learn who has been tasked with taking up the monumental task of FFVII Remake's composition, and to learn if it will simply be updated arrangements of the classic soundtrack or whether it may feature some new musical scores by new artists.