GorakSha is rather unanimously acknowledged as a student/successor of matsyendra in the pan-Indian nAtha tradition. A lot of patina has developed around his historical personage & sometimes he is depicted as even a bit of rival to his mentor. But can we say anything serious about the original gorakSha?
pashchimAMnAya
His teacher matsyendra can be, with reasonable certainty, regarded as an early or even foundational kaula teacher. The kaula-j~nAna-nirNaya can be seen as text with him as the author of the core. Hence, we can say that he was specifically aligned with the pashchimAMnAya. However, his influence was certainly accepted among the other AMnAya-s, e.g., the kashmirian mantravAdin, abhinavagupta, who was aligned with the pUrvAMnAya. In a similar vein we posit that the original gorakSha was a solidly in the pashchimAMnAya tradition & a major teacher of that tradition.
vyAdhi-bhakSha
Among other things he provided an exposition of the bahurUpI R^ik as per that tradition & the yAga of a female version of that deity as vyAdhi-bhakSha-bhairavI among other things. It seems his teaching is where one encounters this female version. Tracing this goddess taught by gorakSha we see that the male version is taught by one of the root tantra-s of the pashcimAMnAya, the kubjikA-mata. vyAdhi-bhakSha, a terrifying rudra emanating from the aghora face. However, kubjikA-mata as has come down to us has some incompleteness.
दश-बाहुं महाघोरं
चतुर्-वक्त्रं सुलालसम् ।
सर्व-वर्णधरं देवं
अथ श्यामं विचिन्तयेत् ॥कपालं चैव खट्वाङ्गम्
अन्यत् परशु-शूलधृक् ।
डमरूं चाक्ष-मालां च
फलं हस्ते निवेशयेत् ॥गज-चर्म-धरौ चोभौ
हस्तौ तु परिकीर्तितौ ।
गर्जन्तं भीषणं नादं
सर्व-कारण-कारकम् ॥भक्षन्तं चिन्तयेद् व्याधिं
विश्वेश्वर-कुजेश्वरम्[The votary] should visualize the god as having 10 hands, and very terrible, with four-faces delighting in self-introspection; having all colors but now (merging) into black; holding a skull, a skull-topped brand, an ax, a trident, a kettledrum, a rosary, and bearing a fruit in the hand; holding up the skin of Gaja with two arms; emitting terrifying roars, the cause of all causes. The votary should meditate upon him, the lord of the world, the lord of the planet Mars as devouring the disease.
There are some manuscripts with teach the female variant of the above deity. It is that tradition which gorakSha preserves. Thus, we suspect the ancestral kubjikA-mata taught both forms with different manuscripts preserving different fragments.