It's hardly possible to render even a single one million-polygon character at a sufficient speed, much less twenty or thirty of them on the screen at once. They may be talking about the CG-models that are used to generate normal-maps (textures containing lighting data). Remember, Doom 3 makes heavy use of bump-mapping. iD Software made high-poly versions of their models, generated normal-maps for them, and then applied them to low-poly in-game models, each consisting of around 2,000 or 3,000 polygons each. These made the models appear detailed, while in reality, they weren't real complex at all.
Besides, I could see the individual polygons on Sonic in an earlier close-up screenshot. That most definitely isn't 1 million polygons. GamePro must be giving out bull or something, because I know it's not true.