Transfering PSN account from PS3 to PS4.

I am currently playing on PS3 with a specific account that I would like to keep when In the near future I move to the PS4 console.This Data is exetremely important as it contains my GTA V Online character which is the main reason of me moving on. I would like to know if doing a system restore before giving it to my cousin would affect my PSN account or GTA V character ( which depends on the account).
Thank you.