Winter wolves in Ravenloft are the standard D&D winter wolves found in any setting and they can speak. They speak aloud in all manner of novels written and set in D&D settings etc.
They lean toward evil but as a previous poster stated that is not always the case and they can be neutral. That is not specifically wrong even in the Ravenloft setting, no DM would be wrong for having all of their winter wolves be NE, but there is still leeway to make them or one particular NPC encounter be a Neutral alignment. It would be very strange to have a good aligned winter wolf in any setting. They are an OG monster in the game, they have a long established history of how they should be portrayed.
Lastly, that image above is from The definitive 3rd edition Ravenloft Monstrous List, a netbook released by the Fraternity of Shadows. Its not a Ravenloft sourcebook, just to point that out in case anyone was of doubt. The main aim of that document is to provide lore about the monsters from all various sources of monsters for a Ravenloft DM to flesh out the knowledge checks that their players might attempt in regard to monsters. I don't disagree with that document that winter wolves should probably all be evil in this setting, but its just a strong suggestion (like most natural animals and beasts are in this setting)