That is why punctuated equilibrium's challenge to orthodox gradualism is immaterial to the question of the truth of evolution.I assume by "he" you mean S.J.Gould and/or Niles Eldredge. Gradualism isn't really a process that would "work" or not, so much as a statement about what patterns we should see in the fossil record, given how evolutionary theory tells us new species arise.
Was he saying gradualism worked or no?
Let's let Richard Dawkins explain it:
Here, then, is our orthodox neo-Darwinian picture of how a typical species is 'born', by divergence from an ancestral species. We start with the ancestral species, a large population of rather uniform, mutually interbreeding animals, spread over a large land mass. They could be any sort of animal, but let's carry on the thinking of shrews. The landmass is cut in two by a mountain range. [A small population of shrews somehow make it to the other side, and create a new isolated population that gradually diverges from the ancestral population. Eventually the two races of shrew become two species. If the second population were to migrate back to the ancestral homeland, they wouldn't be able to interbreed with the first.][T]he likelihood is that the two species would not coexist for very long. ... It is a widely accepted principle of ecology that two species with the same way of life will not coexist for long in one place, because they will compete and one or other will be driven extinct. ... If it happened to be the original, ancestral species that was driven extinct, we should say that it had been replaced by the new, immigrant species.
The theory of speciation resulting from initial geographical separation has long been a cornerstone of mainstream, orthodox neo-Darwinism, and it is still accepted on all sides as the main process by which new species come into existence (some people think there are others as well). Its incorporation into modern Darwinism was largely due to the influence of the distinguished zoologist Ernst Mayr. [The punctuationists asked themselves:] Given that, like most neo-Darwinians, we accept the orthodox theory that speciation starts with geographical isolation, what should we expect to see in the fossil record?
... The 'gaps', far from being annoying imperfections or awkward embarrassments, turn out to be exactly what we should positively expect, if we take seriously our orthodox neo-Darwinian theory of speciation. ... [W]hen we look at a series of fossils from any one place, we are probably not looking at an evolutionary event at all: we are looking at a migrational event....
The point that Eldredge and Gould were making, then, could have been modestly presented as a helpful rescuing of Darwin and his successors from what had seemed to them an awkward difficulty. Indeed that is, at least in part, how it was presented - initially. ...
Eldredge and Gould could have said:
Darwin, when you said that the fossil record was imperfect, you were understating it. Not only is it imperfect, there are good reasons for expecting it to be particularly imperfect just when it gets interesting, just when evolutionary change is taking place; this is partly because evolution usually occurred in a different place from where we find most of our fossils; and it is partly because, even if we are fortunate enough to dig in one of the small outlying areas where most evolutionary change went on, that evolutionary change (though still gradual) occupies such a short time that we should need an extra rich fossil record in order to track it!But no, instead they chose, especially in their later writings in which they were eagerly followed by journalists, to sell their ideas as being radically opposed to Darwin's and opposed to the neo-Darwinian view of evolution ....
... The proper way to characterize the beliefs of punctuationists is: 'gradualistic, but with long periods of "stasis" (evolutionary stagnation) punctuating brief episodes of rapid gradual change'. The emphasis is then thrown onto the long periods of stasis as being the previously overlooked phenomenon that really needs explaining. It is the emphasis on stasis that is the punctuationists' real contribution, not their claimed opposition to gradualism, for they are truly as gradualist as anybody else.
Richard Dawkins, The Blind Watchmaker, 1996 ed., pp238-252