Dan Primack, Erica PandeyPhoto illustration: Shoshana Gordon/Axios. Photo: Christian Marquardt - Pool/Getty ImagesElon Musk's AI startup — xAI — announced that it has raised $6 billion in one of the largest venture capital funding rounds of all time.Why it matters: This could help Musk begin to catch up with ChatGPT maker OpenAI, which he co-founded before leaving in a dispute that's become litigious.The intrigue: Some of the xAI investors, such as Andreessen Horowitz and Sequoia Capital, also ...