A dark forest implies that lots of species advance without destroying themselves. One interpretation of the Great Filter basically states that self-destruction to be an inevitable feature of sufficiently advanced life.
So yes... for the forest to be populated requires the filter to be altered or discarded.
Given the assumption that there are large numbers of intelligent species out there (the universe is vast), unless the Great Filter guarantees that 100% (not 99%, or 99.9%, but 100%) of intelligent species will self-destruct, then these two theories are not mutually exclusive.
Due to the size of the universe (100 billion stars in this galaxy alone), remote possibility has to be treated as absolute certainty, this is why dark forest is such a sound theory.
It seems extremely unlikely that superluminal travel is possible, so at some point intelligent life becomes like magnetic monopoles... maybe they exist, but we're never going to meet while either species is alive. You're ignoring just how huge space is, and how meaningless it would be if a civilization rose and fell a million or a billion light years away.
The Milky Way has a diameter of 100,000 light years, and there are 100 billion stars in this system alone. If only intelligent life arises 1 out of 10 million stars, we are looking at 10,000 civilizations in this milky way alone.
Statistically speaking, even the Milky Way galaxy should be littered with civilizations, with average distances between them measured in dozens of light years, not millions.
It's not so much intelligent life arising that matters... what matters is that they become galactic explorers. Really, there is no obvious reason why any species would want to do that, least of all resources. Besides... maybe life is more rare than that, or maybe intelligent tool users are very rare. After all, a genius that lives in deep oceans of some kind might as well be a clam for all that it might change a life off their planet.
You need a specific formula, and you need to include, "Does not extinguish own existence" at some point between, "Gets tech" and "masters galaxy and becomes threat to all life in universe". That really sounds more farfetched than just... the kind of competitive organisms that make it as far as we do, die off for one reason or another before they dominate a galaxy.
