This answer will vary wildly between programs and departments, and it really depends on the leaning of the professors. Short answer is yes, he is still accepted by historians as important to wider historiography. Historians don’t really ever tend to agree on anything, so academic “acceptance” is hard to gauge as some historians disagree with Marx and others agree.

Additionally, Marx's importance historically goes beyond just his historical materialism, but also in that he presented a structuralist history. History had an end point, that, in his mind was the eventual rise of the proletariat. This structuralist viewpoint was challenged, primarily, by Michel Foucault and the linguistic turn in the 70’s and 80’s, and later by the postmodernist movement. Materialism is also not dead and gone in the field, the torch is now mainly carried by neo-materialism and its assorted baggage. During these two periods the historical field also fractured heavily into different disciplines. Cultural Historians, Neo-materialist, social historians, etc.

Finally, even if the field of materialist history was to “die out” that would not be the end of it. A great example of this is Peter Novick’s “That Noble Dream,” while not about materialism it demonstrates the idea that just because one style of historical thinking has been “disproven” it doesn’t mean it just disappears. It still lives because historians need to be able to contextualize the thinking of previous historians, so while materialism is no longer the dominant historiography, historians still need to understand it in order to understand historians that came before.

So methodologically, materialist history is still incredibly important for the understanding of previous generations of historians.

Speaking anecdotally, within my universities department of history, one of the required graduate courses is a historical methods course. Marx and his theories on materialism and structuralism are central to the course, and some professors identify their work as Neo-Materialist. So his influence is definitely still around, it just may not be the dominant historical method.