Hebrew speaker.

Hebrew did not die. While it definitely was not the language of a nation like it was until the First Diaspora, it was still used in prayer and in rabbinical/religious study.

That isn't to say that Hebrew didn't evolve. Aramaic was a very large influence on modern Hebrew, with German/Yiddish, Arabic, and other languages having spots in it once it was 'revived' for use by Ben-Yehuda. The closest to 'authentic' Hebrew is spoken by the Yemeni Jews, we call this Temani Hebrew. The way to identify Temani from other dialects is that consonants retain their individual sounds, except for one that had already been merged before the Diaspora (ס and ש, which make the /S/ sound as in 'sand' in English)

In essence, Hebrew and all of its pronunciation and grammatical rules survived without losing much at all. The hard question was actually "How are we going to modernize Hebrew?" The answer to that is tons of loanwords.

If you're looking for more books on the Revival of Hebrew, the go-to book is Rebirth, by Devorah Omer... however, this book is in Hebrew and my searches for an alternate language copy has been fruitless... but that makes sense, considering it is a book about the person who changed his entire life and that of his family's in order to influence the Zionist movement to use Hebrew as their universal language. Ben-Yehuda also wrote an autobiography, Fulfillment of Prophecy, which is available in English.

The answers in here so far aren't wrong, they're just missing a key point--there were a large number of liturgical pronunciations, none of which exactly match how Modern Hebrew is spoken.

Modern Hebrew pronunciation most closely resembles Iberian Hebrew, which has the same vowel system and mostly the same consonants. The Spanish Jewish community was always a high prestige one in the Jewish world, even after they migrated from Spain, and at the time it was believed to be more historically accurate than other European Hebrew pronunciations.

However, Modern Hebrew isn't monolithic. The "officially preferred" pronunciation varies a bit from the actual prestige dialect, which has more German influence. Specifically, "r" is pronounced as in German or Yiddish, rather than as in Spanish or Arabic, generally speaking, and the pharyngeal consonants are merged in with other sounds. Those are the case to varying extents in Modern Hebrew, just as they were in older forms of liturgical Hebrew.

Even today (er, 20 years ago) it's not uncommon for religious Hebrew speakers to use their ancestral liturgical Hebrew pronunciation to an extent, even if they use some sort of Modern Hebrew for everyday conversation.

Hebrew had been retained as a liturgical language, so the basic pronunciation was known. That said, there were different traditions of pronunciation which are still in use today. I believe Ben-Yehuda deliberately constructed a system for Modern Hebrew that was a simplified version of the Sephardic pronunciation.