There are a few things you can do to determine if someone is active on Instagram. First, look at their posts and see if they have any new content or updates. If they do, then they are probably keeping up with their account and may be more likely to post new content. Additionally, look at their followers and see if there is a large number of followers compared to their following size. If there is, then they are likely doing something interesting or popular on Instagram and may be worth following for that reason alone. Finally, check out their bio to see if they have any other information about themselves or their work that might be helpful in determining whether or not they are an active Instagram user.