Cyberpunk 2077 (opens in new tab) will get at least as much DLC as The Witcher 3 (opens in new tab), and you can expect information about it to start rolling out in the months and weeks ahead of the game's arrival.
CD Projekt recently hosted a Polish Q&A session with investors where it talked about its upcoming business plans, and one of the topics touched on was Cyberpunk 2077's DLC. The game's developer has confirmed in the past that its overall approach for adding content to the game will be similar to its approach for The Witcher 3 (opens in new tab), and these most recent comments - as translated by VGC - confirm that there will be a good amount of it.
Adam Kiciński, CD Projekt president, said Cyberpunk 2077 will have "no less DLC than The Witcher 3 had", and as far as when those DLCs will be announced, we should anticipate "a similar scenario to The Witcher 3". That means we can look forward to a substantial spread of free updates rolling into the game to expand it in the short term, and at least two major paid DLC expansions to be released for Cyberpunk 2077 later on.
On top of all this, CD Projekt Red is still hard at work on Cyberpunk 2077 multiplayer, which the developer is treating as a separate AAA release several years down the line (opens in new tab) - so it probably isn't being counted among the DLC for the single-player game. The studio has confirmed multiple times that coronavirus concerns should not mean any further delays (opens in new tab) for Cyberpunk 2077, so hopefully we can all expect to bombard CD Projekt Red with "expansion when?!" messages come September.
CD Projekt Red is also planning to make a "full-blown next-gen version" of Cyberpunk 2077 (opens in new tab), but not in time for the console launches this year.