I'm not sure what you're trying to do with the code you have posted there, but it is not actually accomplishing anything.
You are initialising the SoftwareSerial library by telling it you want to receive and transmit on Arduino pins 7 and 8, which do indeed correspond to pins PD7 and PB0 on an ATmega328P, so that is correct.
However, in setup(), you are then modifying the DDRB register to set PB4 (a pin you are not using for serial) as an output, and more importantly, setting all other port B pins as inputs. The SoftwareSerial library automatically configures the RX and TX pin modes for you, but after this you are re-setting the TX pin (PB0) as an input! So I am not sure how you are apparently receiving data at your Bluetooth module.
Secondly, what you are doing in the loop() function there also doesn't do what you want - that is, trying to receive data? All you are doing there, by setting the value of PORTB, you are repeatedly enabling the internal pull-up resistor on pin PB1. This occurs because, as per above, you have all pins on port B apart from PB4 set to inputs. Setting the value of an input pin only changes the pull-up.
I think you should refer to some example code for SoftwareSerial in the Arduino library docs.