I Google'd "Porsche Taycan 30000" and found these sources for the 30k pre-orders claim:

* https://thedriven.io/2019/07/31/porsche-taycan-pre-orders-su...

* https://techcrunch.com/2019/07/29/porsche-taycan-reservation...

There is almost-certainly no source for the "most of those customers currently own a Tesla" statement, because that's not something Porsche would ever disclose.