Iphone stolen, can they see all my info?

I got my iphone stolen from me last friday. I got my friend to try and track it but the app says the phone is dead.
Wouldn't of someone turned it on by now? Why hasn't the app told my friend that its been turned on? Could the person have taken the sim card out and now i can't track it? I told my phone company to suspend it, so no one can use it. Its also locked. Can the person that stole it still be able to get a my info?

If you had a code, the person probably restored your iphone wich means all the information about you is gone.

No they erase all the data. Also you can go to iCloud and do a remote factory reset. Also the reason why the phone probably can't be tracked is because there's no mobile internet data being transferred to it because you suspended your account… That person probably isn't on Wi-Fi…

If the phone is reset, the app would not be able to track it.