A few months ago i had the same issue, and to get it to work i had completely disable asio link pro (even though it wasn't on) then it started working. Multiple asio drivers confuse rocksmith apparently so yeah disable asio link pro/voicemeeter banana etc... if you have any programs such as that just in case.
Buuuuut, so i havent played in a few months (february 11th/12th is when i figured out the asio link pro disable thing), and now im having this issue again (may 25th), ive deleted the ini so it would make a default one, i've tried changing settings in it manually before i launch it, ive made sure asio link pro was still disabled, ive verified game files through steam, ive restarted my computer a few times. cant get it to work, and this is the main reason i havent played this game in so long, because everytime i decided to play again it takes me a few days scouring forums and reddit to try fix it, then im just made that im wasting my time off of work to get this game to run.
If you're still having issues launching the game, can you contact us directly through our support site, or private message on Facebook or Twitter so we can look deeper into this.