"He lives over in the West now."
Translation:Mae o'n byw draw yn y Gorllewin erbyn hyn.
Yes, pretty much.
nawr, rŵan both come from similar older expressions meaning 'right now' ('at/in this hour'), whereas erbyn hyn came with a sense of 'now, and for a while up until now'. Really, though, people use them more or less interchangeably.
Very helpful, thanks. I did originally think it meant 'by now' given the presence of 'erbyn' , which I took to mean 'by' (as in that old chestnut which crops up frequently 'Fydd e ddim nôl erbyn wyth o'r gloch') but your explanation now makes sense of the sentence .