... philosopher says.

It controlled Greece and was controlled by greeks for most of the East Roman empire's history.

Greeks continued to exist and create art during the roman era.

I'm gonna guess neither? Or he didn't really care, since utopia first of all isn't the greek form anyway, it's outopia, as others have said in here. Besides, it's not like the english pronunciation of eutopia is closer to the ancient Greek one than "eftopia". The point of the post the person above the one you answered to was that utopia and eutopia would be pronounced the same, which is false.

Premodern era, like what /u/j4trail said. Ancient era, probably like /u/WaddlingTriforce said. There aren't only ancient greek or modern greek eras. There are a couple of stages in between.

Not only in modern greek. Pronunciation started shifting in the hellenistic era with the koine greek. Also, by the time this word was coined, the 16th century, the pronunciation was "eftopia".