Your tutorial shows how to bias a Jfet that is Common Source. But the datasheet for the electret mic shows the Jfet is a source-follower that is completely different.

Yes, because an electrect without a jfet and loading resistor is about a 1M condensor element.

 

What is the voltage (AC and DC) at the drain of J1? Try various values of R8 until the DC voltage is between 2V and 3V.

Sorry for the slow response didn't have a potentiometer at hand so had to fiddle with a bunch of resistors.

I cant really read any AC on the drain and with the 80 Ohm resistor DC was about 14mV.

With a value of 15k Ohm for R8 the drain DC was 2.47 V