Well, in English, it would be better to say "hop-light" when speaking the English word "hoplite", as this is the standard transliteration of the word and its conventional English pronunciation.

In popular history, terminology and proper names relevant to (and contemporaneous to) the Ancient Greek world are often viewed not just through the lens of the language in which it's being described, but also through an intermediate Latinisation, for all the sense that makes. Consider Mount Hymettus, or the Areopagus, or the popularity of "Hephaestus" vis-a-vis "Hephaisteion" or similar. So we can end up rather alienated from the Ancient Greek, without studying the language directly. But that's the reality of our situation.

Nonetheless, this word (ὁπλίτης in the nominative singular) can be a window into Ancient Greek phonology, so let it be that. In the Ancient Greek, pronunciation of this word will have varied from region to region, but usually, when we're discussing Ancient Greek, we're discussing 6th-4th century Attic Greek. In this familiar dialect, it was pronounced roughly (in vague English transliteration) "hope-lee-tehs". Because English speakers compulsively diphthongise the vowels /ɛ/ and /e/ in a number of phonetic environments (which you've aptly represented with the 'y' in 'tay'), there is no entirely accurate English transliteration here which represents the Greek pronunciation in English orthography (i.e., without carrying along with it English baggage). But "hope-lee-tehs" will have to do. A simple IPA transcription would be /hoplitɛs/.