Is it true that China has better subsystems than the US? I am talking about GaN AESA, spoofing and jamming on planes.
significantly more individual transmit/receive on their AESA than the US counterpart?
We know some characteristics of some old systems which are eventually published and/or leaked. However since this thread is for the J-36 which is a next gen aircraft that is still in development, we have absolutely no idea how well J-36 various subsystems will stack up against F-47 or whatever in development fighter you care to name. They don't exist as a finished product yet.
In general we don't really know much about how good various subsystems are on fighters that are currently being produced. This is partly because of good OPSEC and partly because technology is improving so it's a moving target. As for the general state of industry/tech levels of various relevant fields to fighter subsystems it is probably fair to say that right now China and USA are somewhere close to each other. This could mean there are specific subsystems where USA or China is a bit ahead or behind but in general it's close enough that there is no way to know from OSINT.