Just get it now and update if the 14 Pro is so astoundingly good you can't resist. The video recording capabilities of the current model are very good and either match or far exceed the capabilities of the devices most people on YouTube are probably using.
From a content creation perspective, I don't think many people are currently watching videos in 8K and I don't think that is likely to change in the future (I don't even think many people are currently watching in 4K, for that matter.) Further, the size of 8K recordings is probably still a nightmare to work with.