Just to make this clear, 7% includes all the people that had already bought the game on itch before the update, right? Because people that paid once and now receives updates for "free" should be counted towards the spectrum of paid users. Also people like me that tried the free demo shouldn't be counted as users pirating the content since it's being provided officially, but I'm guessing we also shouldn't make it into the analytics in the first place... Right?
I'm sorry if I seem a little sceptical about those percentages, I know piracy is rampant for games like this one and it sucks that the game is not receiving all the support it deserves. But 93% seems too high a figure IMO.
And speaking of reducing that number, have you tried patreon codes? By which I mean, releasing a full free but limited version of the game, with scenes or content locked behind a unique code that only those who payed for the game receive. I'm not sure why, but pirating webs usually seem to have a much harder time figuring those out.
Other anti piracing methods I've seen are directly locking the content behind a login, be it in-game (like the code I spoke of) or building a game launcher, like Wanderer did. That would allow you to locate exactly who is it that is leaking the game, and ban them from receiving further copies. Sure they could keep making new accounts, but you just have to keep banning them, if you see an account that is being used literally hundreds of times on different devices, then it's clear that one has been leaked. And even if this method doesn't prove failproof, it is a deterrent and should significantly lower the % of pirated copies