Yes he did, according to the news.
https://www.nytimes.com/2017/12/07/us/.../al-franken-senate-sexual-harassment.html
1 hour ago - WASHINGTON — Senator Al Franken of Minnesota announced Thursday he would resign “in the coming weeks” from the Senate after his support among Democrats crumbled, becoming the highest-profile casualty in the growing list of lawmakers felled by charges of sexual harassment or indiscretions.