The FFP doesn't affect PSG on this instance and many sources have confirmed this. Pini Zahavi has assisted Paris exactly for this reason. The plan is to give Neymar a sponsoring contract from the Qatar Tourism Agency for the promotion of Qatar, for a sum of 220M. That way Neymar pays the clause himself with money from the QTA, excluding the PSG from paying anything out of their own books, keeping the club safe from the FFP.
That's why many sources are saying the signings of Alexis Sanchez and Neymar are not exclusive of one another, the PSG wants and will pay for them both.