You have several options depending on what you application requires.

X VAR BYTE
OPTION_REG.7 = 0 ' Pull-ups on for inputs
TRISB = %11110000

' Shift upper 4-bits into lower 4-bit positions.
X = PORTB >> 4 ' X returns 0 to 15

' Mask lower nibble from result.
X = PORTB & %11110000 ' X returns upper 4-bits, 0's for lower.

' Test individual bits one by one.
IF PORTB.7 = ? THEN
IF PORTB.6 = ? THEN, etc,,,