Transfer money from PayPal to Gdax? No way, it is impossible.
The only thing that you can do is just deposit on Gdax using your credit card, but far as i know they are no longer accepting cards.
Is there a fee to transfer money from Paypal to gdax or gemini?
Try to buy on cex.io or changelly, there you are able to buy bitcoins with credit card, and if you want to trade, you can just move those funds to gdax and that is it, it is not that difficult.
You will have to pay a lot of fees, of course.