Menahem Stern, in his volume Greek and Latin Authors on Jews and Judaism, discounts any references to Judaism by Greek authors before the fourth century BCE -- minus Herodotus, who only refers to the "Syrians of Palestine" who practice circumcision.

Plato is skipped altogether; and Stern also notes that “There is no mention of Jews or of the Jewish religion in the existing works of Aristotle, and there is no hint whatsoever that he referred to either of them in his lost dialogues.” (There's a purported fragment of Clearchus of Soli, preserved by Josephus, that describes a "chance encounter in Asia Minor between his master Aristotle and an unnamed Jew form Coele-Syrai"; but this is certainly ahistorical.)

Theophrastus mentions the Ἰουδαῖοι (Judeans/Jews) by name sometime in the 4th century BCE (or early 3rd); but more bountiful material can be found in the 4th century BCE historian Hecataeus of Abdera:

Hecataeus uses also a Jewish source, and it seems that it was an oral one. This is evidenced by the high esteem in which he holds Moses and by his usage of an almost direct reference to the Bible: προσγέγραπται δὲ καὶ τοῖς νόμοις ἐπὶ τελευτῆς ὅτι Μωσῆς ἀκούσας τοῦ θεοῦ τάδε λέγει τοῖς Ἰουδαίοις [= ‘And at the end of their laws there is even appended the statement, that "these [laws] Moses heard from God and declares unto the Jews"’ (slightly modified translation)].

That being said, however, the original texts of Hecataeus are lost – we’re simply dependent on fragments in later authors – and, referring to fragments of Hecataeus as are found in the first century Jewish historian Josephus, Stern comments that “it seems that Josephus had before him a Jewish revision, however slight, of the book of Hecataeus.” So it's hard to tell exactly what the original unadulterated text looked like.

Funny enough, later Jewish and Christian propagandists had no qualms about appropriating figures like Plato for their own ends, and producing a revisionistic history of Greek-Jewish relations and influence. The well-known Philo of Alexandria, echoing similar sentiments by those like the second century BCE Hellenistic Jewish author Aristobulus of Paneas,

asserts (Quis Rerum Divinarum Heres 43.214) that the pre-Socratic philosopher Heraclitus, whose greatness, as Philo here remarks, the Greeks celebrated so loudly, claimed as a new discovery his theory of opposites, whereas actually Moses had long before discovered this very concept, namely that opposites are formed from the same whole. Elsewhere (Questiones in Genesin 3.5), Philo goes even further in asserting that Heraclitus was not merely anticipated by Moses but that he (Heraclitus) actually plagiarized from the Torah "like a thief" (Questiones in Genesin 4.152).

Numenius of Apamea in the 2nd century CE had a well-known saying, "What is Plato but Moses speaking Attic?" This was seized on by early Christian patristic figures; and, e.g., you have prominent figures like Clement of Alexandria, who follows Philo’s “theft” accusation:

There is then in philosophy, though stolen as the fire by Prometheus, a slender spark, capable of being fanned into flame, a trace of wisdom and an impulse from God. Well, be it so that the thieves and robbers are the philosophers among the Greeks, who from the Hebrew prophets before the coming of the Lord received fragments of the truth, not with full knowledge, and claimed these as their own teachings, disguising some points, treating others sophistically by their ingenuity,and discovering other things, for perchance they had the spirit of perception.

Man, I wish that little alert system hadn't missed this one!

First: given the way you've phrased the question--entirely unlikely. This gets into the problem of canon and when the canon of the OT (I prefer the term Hebrew Bible [= HB]) actually came together.

Second, I'm generally skeptical of most suggestions of early Near Eastern influence on Hellenic stuff...largely because the only ones who would have been capable of doing it would have been the Phoenicians and they weren't responsible for much of any of the text of the HB.

I don't know enough about Homer, but one could likely make the case that flood myths/narratives were more globally pervasive and that it would be difficult to pin the influence explicitly on Semitic origins. (I'd be open to hearing the argument, though!)

Either way, we really have to address the ability for texts like this to move far enough that they could have been encountered by Hellenic/Hellenistic individuals (on top of the fact that they'd need to be translated). Greek translations weren't made until the 2nd-1st centuries BCE...so, late, comparatively speaking.

Much of the OT wouldn't have been written yet, or was in the process of being written, and wouldn't have been translated into Greek yet either. I'm not sure Athenian Greeks in the 5th Century BCE would have even heard of Judaism. Herodotus mentions Palestine but not Jews.

When you delete the top comment and other top comments but leave certain ones that rebuke them it becomes extremely hard to understand what is being said. I know you want sources cited and how strict the rules are here on what is posted, but if your going to delete every third post including the top one please just delete them all. So for example the second post on here is a "good" post so if your leaving the good post leave the one it is in response to! Or just edit their post or mark it in some way with flair so we know it doesn't follow the rules. Still delete ones like this one that are way off topic but please do something different. Staring at a wall of grey "comment removed" littered with a couple actual posts is ridiuclous*

I wouldn't know how likely it would be that the 'Old Testament' would have 'made it' to Athens at the time of Plato/Socrates, but it's interesting that Republic starts in the 'Piraeus' area of Attica (a port/maritime place, just outside the city of Athens itself), which is an area famous for being full of foreigners and their practices. Republic actually begins with Socrates and his companion watching a procession by worshippers of a goddess called 'Bendis' - Socrates (or rather Plato as Socrates) comments their festival is 'as splendid as any Athenian one'. This would likely be the part of Athens in which Jews and others familiar with the 'Old Testament' would be hanging out and practicing their faith[s] most openly.

We know so little about Socrates, that answering this question about him is next to impossible. Given his inquisitive nature, he could have questioned some Jews about their faith, and more than likely try to dissect it with his scepticism, but I doubt he actually read any Hebrew texts, even translated. His hatred towards written word was well known.

As for Plato, it is quite likely that he was cognizant of the tenets of Abrahamic faith, and maybe heven read a transcript of Old Testament, or at least an abreviation of it.

In his later years, Plato and his students borrowed a lot from the Pythagoreans, and dabbled in various forms of gnosticism and misticism, which was a bit similar to monotheistic faith. Plato never explicitely uses and abrahamic religious terms, but his philosophical system shares at least superficial elements with jewish teology.