How many likes do I need to get for an idea to be approved

I don't there is any specific number. It's basically up to IMDb. To answer your question from another post, IMDb post for suggestions about interests is here: https://community-imdb.sprinklr.com/conversations/data-issues-policy-discussions/interests-interests-suggestions-feedback/67225803015c37192f745590 But I'm not sure it will help to post there since there are many suggestions there that haven't been addressed by IMDb.