My dog cut his penis on the gate at my house. But it the inside of his penis and he has been bleeding is there anything I can do to try and stop the bleeding

A vet.

Yep, a vet.
That could turn very nasty very quickly, you need to see a vet!

I will 3rd the motion. Yikes.
If your not going to take him for some strange reason, try and wash it with epsom salts to avoid infection, but seriously, if it has been bleeding all day, this could end very badly for your dog.

Me four.

Vet

Now

Infection has already started to set in, most likely