I have no idea and probably not, but it is a bit more complex than that. There isn't any particular rule saying that the only functional democratic model is multi-party democracy. One could imagine a successful democratic model with one party allowing diverse internal factions, for example. It is really hard to get a read on China, but their success raises some interesting questions of how exactly their internal party decision making is set up.
That being said, I would assume that a one party state isn't very democratic. It'd be an unstable democracy.
been in China for decades, benevolent dictatorships allow long term planning, elections every 4 years favor short term decisions, populism and waste a huge percentage of time in after elections and pre-elections
China and Singapore showed democracy is not necessarily the most productive way to run a country
From what I've read (and this may very well be outdated), Singapore is generally democratic, but the PAP does such a good job of running the country that people don't vote for other parties.