A modern French pronunciation would be something like “tee-BAW”. Shakespeare anglicized the name to “Tybalt” in Romeo and Juliet. Thibault’s own father spelled his name “Thibaut”, and they were from Flemish Antwerp, so the “Thibault” spelling is a French styling.
Lacking the man here to correct us, I’d say either “tee-baw” or “ti-balt” is acceptable in English. I use both basically interchangeably.
NoCo Thibault Rapier 