By default, the Fitbit tech stack doesn’t sync with the Health App on an iPhone and iPad. But never fear, as with basically everything else on this planet, there’s an app for that!
From the iOS App Store, search for Sync Solver. Using this app, you can then link your Fitbit account to your Apple Health app.
Once linked, you can use the Sync Now button to do an immediate data sync or you can do an automatic sync at midnight every night. And presto, you then see your Fitbit data in the Health app. Happy waiting for the Apple Watch to come out!