After someone on Mastodon referred to Voltaire in a thread about free speech, and because a few days ago in a thread I mentioned Meindert Fennema who apparently also referred to Voltaire, I've search for fact checks. Found two results.
Fact check : Did Voltaire Say, ‘I May Disapprove Of What You Say, But I Will Defend To The Death Your Right To Say It’?
Conclusion : no

It was once an article of faith that even those who speak words we disagree with deserve protection. As regards Palestine, that’s now not true, says Mehdi Hasan, editor-in-chief and CEO of Zeteo
"Se volete assomigliare a Gesù Cristo, siate martiri e non carnefici"
( #Voltaire, 1694-1778)