This is Julian fr. 161 Bidez, quoted again at iota 437. Empedotimos is also mentioned in one of Julian's Letters (89b, line 186: 'Socrates and Dio [Chrysostom] and the great Empedotimos'), and by other writers such as Damascius and Proclus.
Nevertheless, some modern scholars doubt his existence; cf. the summary in Schneider & Goulet. The doubters regard him as a literary creation, in Heraclides' dialogue called (probably) On the soul; so e.g. RE Suppl.IV (1924) col. 269. There, Empedotimus of Syracuse is the counterpart of Er the Pamphylian in Plato's Republic, in that both have revelatory visions.
As to the name Empedotimos itself, F. Wehrli and H.B. Gottschalk have suggested that it is a fusion-construct, by Heraclides, of Empedocles and Hermotimus (of Clazomenae, a Pythagorean philosopher of the C6 BCE mentioned by Aristotle, Pliny the Elder, Plutarch and Lucian, amongst others).
For a recent discussion, unimpressed by the arguments against the historicity of Empedotimos (who does bear a name independently attested as that of real individuals), see Kupreeva 96-99.
[1] Heraclides [eta 461] fr.92 Wehrli, 53 Schütrumpf. The Suda's words kai\ mikrw=| pro/teron might (as here, and cf. iota 437) be presented as being quoted from Heraclides. The main reason for thinking so is that otherwise Julian would seem to be guilty of the egregious error of dating Heraclides (C4 BCE) later than Iamblichus (C3/4 CE: iota 27).