Hi,
I think you may find such examples anywhere.
If you need to copy the state of one port to another then the simplest way is just connect them together (=
By software it is done with two commands:

	SETB	P3.7		; set pin as input one
CYCLE:
	MOV	C,P3.7		; image input
	MOV	P1.1,C		;	     to output
	JMP	CYCLE

If you need to toggle output on each button action then you must know something about signal debounce:

	SETB	P3.7		; set pin as input one
CYCLE:
	JB	P3.7,$		; wait for button pushed
	MOV	R0,#40
PUSHED:
	JB	P3.7,CYCLE	; debounce
	DJNZ	R1,$		;	  negative
	DJNZ	R0,PUSHED	;		  edge
	CPL	P1.1		; toggle output
RELEASE:
	JNB	P3.7,$		; wait for button poped
	MOV	R0,#40
POPED:
	JNB	P3.7,RELEASE	; debounce
	DJNZ	R1,$		;	  positive
	DJNZ	R0,POPED	;		  edge
	JMP	CYCLE

Here the DJNZ is used as debounce cycle. Please understand that it is not a good idea. Probably you should use timed intervals to not be depended on OSC frequence used.
Good days!