I've also heard that @pacothetaco2003 got some evidence but he has not posted it yet. I was not currently online at the time.
Whether or not he actually is capable of doing so isn't the question. As far as I know there are severe consequences for threats of hacking accounts, DDoS threats, and other related threats. I believe that some players have been banned as the result of such behavior.
I think hacking accounts is not a ban able offence. But you do have evidence if he does what he said. If he does hack your account you need to provide evidence witch you have and a screen shot of you being kicked out of you account.
Obviously this was all just a joke. 1. They can't hack into your account without a hacked client or some hacker tool 2. It was just a sound of speech to threaten you. If you are scared, change your passwords to your Mojang, email and minecraft password.