At least 40h/week in total, can be split between multiple people as long as they are employed long-term.
see also:
Will Manifold moderation get significantly less laissez faire by the end of Q1 2024?YES
Will Manifold implement features meant to protect new users from being taken advantage of by the end of 2023?NO
Will Manifold hire a professional market creator by the end of 2023?NO
Will Manifold hire a professional market creator by the end of 2024?NO
1,000
3.00Why would they?
There are currently a lot of very enthusiastic market creators doing a good job of creating markets for "free" - either for Mana and leaderboard points or because they are passionate about certain subjects which they would like to see market estimates of.
Why would someone being paid by the hour do a better job?