For what it is worth the graph below shows a search for some big name economists in Google Ngram Viewer.
It has to be admitted that one cannot really search effectively for references to Adam Smith by using “Smith,” because, needless to say, it is the most common surname in the English language. Nor does “Adam Smith” alone really provide a good index to references to Smith.
And the data must be distorted by the fact that there are many instances of “Keynes” and “Friedman” that do not refer to the economists, such as, for example, “Milton Keynes” (a town), “John Neville Keynes” (Keynes’s father) and “Thomas Friedman” (the journalist). Of all the names, I suspect that “Friedman” is the most distorted, but, nevertheless, there is reason to think that Friedman did eclipse Keynes in citations in the 1970s, so perhaps the graph does capture roughly the frequency of citation of these economists.
And the frequency of citation of Keynes soared in the 1930s and was predominate until the early 1970s, which is what one would expect.
Moreover, the citation of “Mises” and “Hayek” is fairly low. The name “Hayek” rose somewhat in the 1930s after Hayek’s appearance at the LSE and the publication of Prices and Production but then fell. After the 1970s it rose again, with the revival in interest in Hayek’s work and his Nobel Memorial Prize, but has never rivaled the frequency of citation of Keynes’s name.