Musk is a cunt and Tesla are shit

sadly, any negative press seems to barely affect it.
Tesla are the some of the most dangerous cars* on the road, yet people are queueing up to buy one.

*drivers cause most crashes, but autopilot has its fair share of blame

Does he have any cash or is all his wealth in shares?

He has lots of liquid assets (probably billions of USD), but not enough to cover the entire Twitter purchase, so if Tesla crashed, and other things fell a certain way (e.g. he wasn't bailed out by someone else or wasn't able to borrow against other not-so-liquid assets), it could theoretically bankrupt him.

Apparently he had to borrow to buy Twitter.

Rich people have the luxury of not having to buy things with their own money. The richer you are the more access to credit you have and so the more you can buy with other people's money.

Does he have any cash

The cash he has mainly comes from the sale of Tesla shares. He has sold around $25Bn of them in the last couple of years.