There has certainly been huge GDP growth in China but their specific claims about GDP can't be attempted to be believed. Their numbers have never been independently verified and most of the raw data is treated as a state secret. There is reason to suspect that some of what they're reporting is just made up. Party officials are evaluated based on meeting certain economic targets so there's a lot of incentive at the lower levels to falsify data. The same thing happened in the USSR before it collapsed (I'm not suggesting that China will collapse any time soon, just pointing out that this is a common pattern in single-party authoritarian governments). External estimates based on resource utilization indicate that real GDP might be significantly lower.