Proposal came from Sergey Karginov (Liberal Democratic Party of Russia), but I wonder if there is interest in the Russian government for China helping them either
- repair the Kuznetsov or
- build a new STOBAR carrier or
- build a new CATOBAR carrier
Kuznetsov is pretty much a gone case - With how many times that hull has set itself on fire by this point - Together with the state of neglect and disrepair of the ship itself by the crew and the navy. Sure, China can provide some help to repair the Kuznetsov, but there isn't really much that China could do, if the aim is to bring Kuznetsov back to its intended glory days.
Regarding the later two, meanwhile... I don't think that the Russian Navy themselves would put their focus on larger surface warships for at least the next decade or two. Their attention and effort are better spent ridding as much nepotism, corruption and incompetence from the armed forces and the military-industrial complex as possible - Plus making sure that their present smaller warships and submarines are in good, servicible order.
On the other hand, all the weaknesses associated with STOBAR carrier have been pretty well understood by China, hence I believe China would not recommend a STOBAR solution for Russia either.
Besides, the main problem with steam-powered catapults being rendered dysfunctional due to the cold temperatures in the Arctic feeezing the steam is nonexistent with the EMALS catapult system. So there is another bonus point for a Russian CATOBAR carrier.
Hence, if anything, China could build a CATOBAR carrier for Russia - But only after China has enough CATOBAR carriers of her own and having shipbuilding capacity to spare for Russia.