There are two questions here.
1.) Can China control thousand and thousand of drone.
2.) Can drone pin down the Taiwanese defence when troop come ashore.
For number 1. I don't know, not an expert on Chinese Aerial Capability, I have no exact answer to this question. All I can say is this. For this to happen, there are a lot of communication going on simultaneously Say you have 10,000 soldier controlling 10,000 UCAV, does that mean you can effectively control those 10,000 UCAV and engage their target as you progress?
Look at it this way, it is very obvious you will need to have a target for you to attack, so how are you going to find that target, and to what mean you know that is the target you want to attack first? UCAV does not carry unlimited ammo you know. The first part is easy, you go find a target either by ground troop feeding your target from the ground while they are fighting, or you have enough AWACS up and they pick up sea/ground/air threat as they go along. The second parts is a lot harder, because if this is a ground feed, it's what we called a "Localised" target, that is the only target you see, while you don't know what that is or how important to the situation at hand (ie the landing) everybody wanted their target to be attacked first, and in a big battlefield, there are a lot of troop calling out a lot of target all at the same time. On the other hand, if that is a AWACS fed, you will know all the available target in the area, but you won't know what is what, AWACS can detect threat, but it wont tell you what it is. So, without complete Battlefield awareness, your drone will be just blindly attacking target as it goes, that would not improve battlefield efficiency.
For number 2. Drone don't carry wonder weapon, at best you will get the same weapon you are carrying with a ground attack aircraft, but with lower number. It is tried and tested that no airpower can change the outcome of a battle, same with manned platform, you still risk being shot down and not be able to engage your target, the only thing you get is preserve your pilot, it does not really do much on the frontline with troop is fighting. On the other hand, missile and bomb used on drone are the same used on Attack Helicopter or Strike Fighter. If a target is immune from air attack (like in a bunker or underground structure or heavily defended by Anti-Air. Your outcome is the same. And believe me, Taiwan probably already have their structure hardened from air attack since air power come to term. So what left is what we call soft target, the tanks, the APC, troop masses and so on, it's not really easy to locate those stuff on battle. That is the reason why drone didnt change much of the landscape of Eastern Ukraine for the Ukrainian
Introducing Drone in the battle is probably going on the same axis as introducing air power into battle. The only different is just that you are not risking a pilot to do that. And for frontline troop defending those beachhead, not killing a pilot is probably the least of their concern, it's that 10 of thousand of troop that landing ashore is the problem, not the guy who fly from behind enemy line.