Here's the voice actor for "Male1" voice celebrating how he just recorded the last lines for the role.
https://twitter.com/JoshWichard/status/1672203001698611200He claims 4203 lines recorded, which is a fraction of what other actors declared for companions (the guy that voices Astarion claimed 30K+, for context).
The implication is that like in the current build "Tav" will voice only some occasional bark or special dialogue here and there and for the rest will remain a mute protagonist.