The new Encyclopedia Judaica is not so sure, citing the work of historians, archeologists and others. YU's Rabbi Shalom Carmy responds this way:
Orthodox Rabbi Shalom Carmy of New York's Yeshiva University grants that historians have so far found no documentation on Moses apart from the biblical writings. He doesn't find this gap surprising and says scholars who make that argument fail to acknowledge that evidence corroborating ancient texts is very spotty.
Summarizing the Jewish divide, Carmy observes that liberals hold the biblical text "doubted until independently proven true," while for fellow traditionalists "it is true unless conclusively disproved."
Really? A less-than-6000-year-old-universe has been conclusively disproven, yet most of Rabbi Carmy's "fellow traditionalists" still posit a less-than-6000-year-old-universe. And, one should ask, what would Rabbi Carmy do if large parts of the Torah were proven false? You know the answer to that question. Rabbi Carmy will continue to believe, will continue to maintain even those parts of the Torah are true, and will continue living his Orthodox life.
In Rabbi Carmy's mind, the Torah can never be wrong and can never be proven wrong. Therefore all proofs are not conclusive. Follow that reasoning? It should sound very familiar to you, especially if you were ever a Moonie or wore orange robes.