Natural speed please Thank you
"How long are you here for" is suggesting that you are already at a location
and a person is asking for how much longer will you be in that location.
"How long are you here for?" "I'll be here until 3:30"
"Josh, how long are you here for?"
A person is asking "How long is Josh going to stay at a place?"
"I'm here for 10 more minutes"
I arrived at some point in the past
(it doesn't imply anything about how long ago that was),
I am here now, and I will depart 10 minutes from now.
How long are you here for? = How long will you be staying here?
I'm here for a week. =I'll be staying here for a week.