And is this the confirmed location or a guess?
Confirmed. Vladimir Putin and Bernie Ecclestone are there now.
the layout would be quite good if it has some nice elevation changes
No elevation changes. The elevation around Sochi is so extreme that you can’t actually build on it. Not without having hairpin after hairpin as the road climbs the side of the hill.
Besides, you don’t need elevation changes to produce good racing. Silverstone and Monza are two of the most popular races on the calendar and they have very little in the way of elevation changes.