The details of Durgnat's significance as a film-critic can be found on this Wikipedia page. As the bibliography shows, the majority of his works focused on particular film-makers or particular films, but there are some general-theory works. I assume that most of these tomes were, as is traditional in the world of academic publishing, cobbled together from separate essays written for magazines like FILM COMMENT or SIGHT AND SOUND. The Wikipedia page mentions at least one essay that he worked into the book that most resembles a "general theory of film aesthetics," the 1967 FILMS AND FEELINGS. I can well believe it that this book originated as an assortment of essays on related themes, for most if not all chapters are just a few pages long.
Doing a variety of searches on the web for Durgnat and related topics, I don't get the sense that the legacy of this once influential critic has had much impact on current Internet film-writings. Nor did I get any sense that the worlds of elitist comics-criticism were even slightly acquainted with the man; combined searches of Durgnat's name with those of THE COMICS JOURNAL or THE HOODED UTILITARIAN yielded nothing of substance. (As I opined in an earlier piece, I was surprised when I learned that some HUddite even knew who Northrop Frye was.)
There are probably more differences than similarities between the myth-critic Frye and Durgnat the "radical populist" (as the Wiki essay calls him). Still, they share a concern with the idea that popular art is not radically estranged from "high art." On the first page of FILMS AND FEELINGS, Durgnat asks rhetorically:
To what extent does criticism habitually dismiss as "bad art" films which are "coarse-grained"-- but authentic and rewarding-- and so falsify its view of the medium?
Durgnat does not quite explain what he means by "coarse-grained," but I think it likely that he was contrasting "coarse arts" with "fine arts." Chapters in the book defend such "coarse art" as 1945's THE WICKED LADY (about a female highwayman) and 1955's THIS ISLAND EARTH (Earthmen dealing with alien imperialism). The first film Durgnat mentions in the book is Nicholas Ray's 1954 western JOHNNY GUITAR, and though he freely admits that he doesn't claim that the film "is a masterpiece," but he does say that it "typifies the interesting dramatic and moral points, and 'resonance,' of a competently made film." His aestheticized populism is also displayed in the first chapter, where he emphasizes his ambition to "find not only some 'lowest common denominators,' but also some 'highest common factors' of taste, and to do so, less by theory, than by exploring specific films."
As the previous sentence attests, FILMS AND FEELINGS does not dwell on pure theory. I imagine that like most writers of the period, Dirrgnat took some influence from the Marxists film-theorists of the day, though he seems to me far less agenda-driven than a contemporary like Robin Wood. It may be that his type of criticism has been pushed off the stage by the extreme ideologues, though I imagine that some modern readers may still yearn, as I do, to see what the critic called "the wedding of poetry and pulp."
More on Durgnat anon.