Debounce counter for PIC micro - Suggestions for improvement
Device selection
I guess the reason you're on the PIC16F57 is that you're a hobbyist, and this device was the one on hand. I can nearly guarantee that, for a production application, you can find a device from Microchip that is newer, cheaper, smaller and more capable.
One change that most new PICs include is selectable Schmitt-trigger input mode, which will help with your debounce or even eliminate the need for software debounce, depending on your specifications. Your current device has no Schmitt trigger selection register (chapter 6), and only a limited number of special-purpose pins that have Schmitt trigger inputs (chapter 11.3).
Another feature you can take advantage of is software-enabled weak pullup, which - given that you're monitoring a button - is likely to simplify your circuit, which you have not shown. This is commonly available in new PICs.
Yet another feature you could use is integrated pin change detection, commonly available in new PICs - the IOCI module. This can potentially reduce your power consumption, since you wouldn't have to run a polling loop - you could set up a timer, set up IOCI, and then if the timer fires before an IOCI the button event is valid. If an IOCI fires before the timer expires, reset the timer. Some devices can actually go to sleep while this happens and wake up for either interrupt.
Typo
overflown = overflowed
Assembly
I don't recognize the flavour of assembly you're using, perhaps because I'm used to the assembler bundled with contemporary releases of MPLABX. But any self-respecting assembler should be able to:

Accept 6 instead of 0x06, the latter having no need for hexadecimal representation. The same with 0x00.
Include a device-specific header file with symbols for PORTB so that the magic number 0x1F can be replaced by what you're actually doing, which is

andlw PORTA0_MASK |
      PORTA1_MASK |
      PORTA2_MASK |
      PORTA3_MASK |
      PORTA4_MASK;

All (official) PIC environments offer such symbols in their header files, and using them will make your project more maintainable.
General approach
It seems deeply strange to me that you're debouncing five buttons all at once. I would expect, for the current device you have,

Poll for one button press - you can check all pins of PORTA at once using the Z flag
When you hear a button press, assign a mask variable that monitors only that button pin
Poll until either the time expires (you can use TIMER0 and its prescaler to get 32ms) or the button is released
Poll on that pin only, using your mask, until 32 ms are up

For most applications you'll only care to process one button at a time.