how can i get the copy rights for fnaf

I think that you meant can you Monetize with Five NIghts at Freddy's videos that you make. I can't find official game page for Five Nights at Freddy's so you can try actually contact maker of this game via e-mail or other ways. Game web page seems to be http://www.scottgames.com/

Many times you can find information about Youtube and other means for monetize your videos from game related webpages or even try to find if game is on some kind of list pages like

https://www.reddit.com/r/Games/comments/1egayn/lets_build_a_list_of_game_studios_that_allow

You can find some games/gamestudios monetization policies from this or similar list. Or if they cannot be found, contact makers of game which material you want to use with your monetized videos.

Even you get rights to monetize with some games, please note that many games uses music that are licenced from 3rd party, so you can get content-id claim for this video. So always try to record you material without music. Helps also with editing and there is plenty of great music to use on you videos via Freedom.tm and some other sites/composers like Kevin MacLeod incompetech.com/ that gives music for free for you projects (you need to mention them on your video and what song you use)

Hope this gives you some information about Youtube monetization.