Too little is known about the philosophical and religious beliefs of the historical Socrates, which are known to us mainly through the writings of Xenophon and Plato, to assign Orphic origins to any of his beliefs.
It is widely thought that the early Socratic dialogues of Plato reflect the historical Socrates' actual views or something very close to them but even this is unprovable. We don't know what Socrates believed except insofar as these views are refracted through the lens of a philosophical genius, Plato, and the intellectually pedestrian figure of Xenophon. (Which is not to dismiss Xenophon as a worthless witness.)
Russell at his best was a philosopher of immense greatness. Russell as a historian of Western philosophy is no safe guide. Try C.C.W. Taylor, 'Socrates - A Very Short Introduction', Oxford, 2000. This at least is the work of a philosopher, historian and Greek scholar. Our knowledge of Socrates is too frail a web to be handled by Russell's rough fingers.