Generally, people can find out if you view their Instagram story. This is because Instagram has built-in tracking mechanisms for that. However, there could be rare glitches or special settings that might affect this visibility.
In most cases, they can. Instagram usually shows indicators or notifications when someone views their story.
Yes, they can. Instagram has features that let the person who posted the story know who has viewed it. But sometimes, depending on privacy settings or specific circumstances, it might not be 100% accurate or visible to them.