Do they mean gameplay(more traditional 3D platforming?), because looks-wise, Dark Souls looks NOTHING like CV. I'd go on to say it looks as much CV as LoS does.
In regards to gameplay, Souls' combat is more tied to Castlevania's combat, rather than its platforming. Both emphasize a sort of caution and puzzle-solving that LoS and other brawlers lack. That combined with the weight and emphasis on truly understanding how you and your enemies move is at the heart of both Souls and classic Castlevania.
The way they describe the non-linear progression also seems to link it more to Castlevania than, say, Elder Scrolls.
I think looks-wise, it's a lot closer to Castlevania. It's a rawer western fantasy akin to Super Castlevania IV, without the influences of DnD and etc. Admittedly, most other Castlevanias are more about a whole slew of mythologies or about a castle full of pulp horror movies. Of course, if you want to go into that pulp direction, Souls covers that with its music.
In any case, it's okay that Souls is striving to be more than just something Castlevania anyway. Worked for Devil May Cry!