Where's the switch supposed to be in your schematic? (I assume you are talking about a push-button to turn the circuit on, or are you referring to the MOSFET itself as the switch and it's being controlled by the PIC?)
Is the switch supposed to power up the circuit including the PIC? Then the PIC keeps the MOSFET on until it needs to be turned off?
We need a bit more information, particularly about the switch and where it fits into the circuit.
But, if you're referring to the MOSFET itself as the "switch", yes, the circuit as you posted will work (the drawing of the MOSFET is a bit confusing, the gate is hard to distinguish). I've done the same thing in a circuit to act as a self-power-up button. Press the button and it turns on the MOSFET which powers up the load (including a microcontroller) which in turns keeps the MOSFET on via one of its I/O pins. When the MCU wants to cut power, it sets the pin low, turning off the MOSFET.