I think this is a misunderstanding of the piece and how journalists typically paraphrase things. The reporters wrote that Ilya told them that results from scaling up pre-training have plateaued. So he probably said something to that effect, but for readability and word-count reasons, they paraphrased it.
If a reported story from a credible outlet says something like X told us that Y, then the reporters are sourcing claim Y to X, whether or not they include a direct quote.
The plateau claim also jives with The Information story about OpenAI, as well as a few other similar claims made by people in industry.
Ilya probably spoke to the reporter(s) for at least a few min, so the quotes you see are a tiny fraction of everything he said.
Thanks for these!