The Frankfurt School did not settle in the US but fled Germany in the mid 1930's because they were on Hitlers hit list. If you had bothered to consider the links I posted you would know that I am well aware of that. Their influence on the Spartakusbund had riled not a few Germans for having turned Berlin into the equivalent of modern San Francisco. It scared the hell out of German conservatives, many of whom fell into Hitler's arms in the election of 1932.
As far as their present influence the FS ceased to fashionable among the western left in the early eighties.
The standards they set as adopted widely in the '60s and '70 live on. Marcuse is still called the "Father of the New Left."
They are most definitely not responsible for the emergence of multiculturalism which is a product of French Post Modernist epistemological scepticism.
I believe it was someone else who said that they were responsible for multiculturalism.
Marcuse was the idol of the French New Left in the early sixties. By the eighties he was no long influential in North America.
From my own experience I came to the FS quite late in the mid eighties when the Lacan and Beaudrillard were the latest fashion.
I found French writing of the period to be completely hostile to rational thought and in fact nihilistic.
Not to mention both Lacan and Beadrillard were gay and Lacan died of aids. The notion that all narratives have equal value is equivalent to 'all behavior has equal value'. In the context of AIDS this is not just false but lethal.
As far as the FS is concerned I think Marxism entered its theological faze in the early fifties.
In short Marx's incorporation of Hegelian Dialectic into the notion of dialetcical materialism put an end to Marx as a serious historian and philosopher.