If I have multiple YouTube channels per single Google account and Google decides to block one of my channels, what about other channels? What about my Google account?
As far as I know, Youtube doesn't block a single channel, it could block a single video and after the third strike could terminate the Youtube account. From Account terminations - Youtube Help
Users whose accounts have been terminated are prohibited from accessing, possessing or creating any other YouTube accounts. When an account is terminated, the account owner will receive an email detailing the reason for the suspension.
Since Gmail is the default email service for Youtube accounts, I think that the Google Account will not be blocked, just the access to Youtube with that and any other account for that user..
To learn about Youtube community guidelines strikes see Community guidelines strikes - Youtube Help