Unless it is something as critical as Syria leasing an entire port in perpetuity to China (ie:Latakia), I can't see how Beijing is going stick its hand into this quagmire. Even then such an offer would be one of doubtful value. The Mediterranean is basically a closed off bowl, if Syria was sitting on the Indian Ocean, doubtlessly China would have jumped on the prospect of having such a foothold.I wouldn't believe them unless we get official confirmation from Chinese authorities. Russia would love for China to share a part of the burden, but what's in it for China?
Russia is going all in because it needs to maintain it's Tartus naval base as a vanguard to the Black Sea area.
In all honesty I won't be surprised if China has deployed covert intelligence assets to both survey and advise the Syrian forces but that did be the limit of what they are willing to do, apart from selling them weapons via 3rd party connections but lets be honest everyone is doing that at the moment. With all the weapons, factions and doctrinal tactics involved in Syria, that place is an intelligence gold mine.