In most areas, western technology and capability, given the will, still leads China. However, China excels at getting capabilities fielded and generally benefits strongly from a unified desire to leap ahead. They can often accomplish things that are potent, but executed in a cruder way than would the west. No matter though, if they can field the capability and it is "good enough".
At least in the U.S., profound dysfunction and misalignment of incentives exist between high-level intent at the Secretary of Defense level and fielded capability.
A historical trope was that the Chinese are not creative problem solvers or researchers, unlike the west. Anyone paying any attention to relevant technical areas should be thoroughly disabused of such thinking. There is some impressive conceptual work China contributes to the technical literature.
Their first reusable rocket is due for a test launch in a few months, their second domestic carrier is in construction, and in hypersonics they are, by the DoD's own admission, well ahead.
They have a fully domestic rocket online with a launch reliability over 94%, and their launch cost is only barely higher than that of the Falcon 9, at around 70 million dollars vs 50 million. They are also building a super-heavy, 140 000 kg LEO rocket.
In silicon tech, they have a 14nm fab online, which is hardly "decades behind".
In sat tech, they have pretty much all they could ask for.
I don't really get this viewpoint. China doesn't really advertise their capabilities, but it's clear that they aren't far behind in more than a few crucial sectors, and clearly ahead in others. At this point they are near competitors of the west.