Will an exporter be required to pay GST in case of goods procured from unregistered persons (including unregistered job workers)?

In case of supply by an unregistered person (including unregistered job workers), the registered person i.e., exporter shall be liable to pay GST under reverse charge mechanism.
However the exporter can avail ITC of such GST paid and either utilise the ITC or claim refund of the same.

(FAQ-21 :Exports)