And when this growth ends, what will happen? An authoritarian system is able to withstand challenges with the full power of the state behind it. People that dissent are crushed, and many times the people that dissent do so with the most honourable of intentions. Viewed under the prism of authoritarianism this matters not. It's a system that remains not because of consent and merit, but ultimately due to suppression of dissent.
Just because China is able to catch-up some of the growth that it completely missed out on due to the turmoil of the Communist revolution and the turbulent 50s and 60s, doesn't validate this system one bit. Other countries were ahead of China, with more growth and sustainability, minus the cruelty.
The most powerful countries in the world were literally coasting on stolen Chinese wealth for 100 years of so. When the UK couldn't coast anymore, it lost world reserve currency status.
Now, can we get back on the subject of how the CCP is treating dissidents (and neighbouring countries)?
India springs to mind as a good 1:1 comparison candidate and it seems to be doing much worse than China in most economic metrics.
Just because they both have large populations don't make them alike.