If I Baited Hook a unit and Soraka keeps it from dying, do I still get to grab a unit off of the Baited Hook?

No. Because Soraka's replacement effect means the unit is never actually killed, Baited Hook has no "killed unit" to reference — so you look at the top 5 cards but can't play any of them, and you recycle all 5 (RiftJudge FAQ #10387; Rule 359.3.e.12). Your original unit stays in base (exhausted and recalled), so you keep it but get no unit off the hook.