Depends on how you want to measure revenue. YT itself is a massive cash hole. It's the advertising that carries it. YT Red (and other types of paid service) are

Depends on how you want to measure revenue. YT itself is a massive cash hole. It's the advertising that carries it. YT Red (and other types of paid service) are bumps in the economic redline. "Google has never revealed YouTube's revenue" but you can quantify it (roughly) from known values and costs. Ultimately profitability of a product within Alphabet depends on how you want to categorize technology within Alphabet. DFP and YT, at the very least, are separate products.