but I need to know the max receivable mAmperes in order to put another correct resistance between the button and the input pin.
A pin when it is an input is very high impedance so the current does not matter, you need not be concerned about it. That means you can remove R1 altogether and replace it with a wire.
The purpose of R1 is to act as a bit of protection in case pin 8 gets set as an output and that output gets set to be low and you push the button. In that case that pin will be sinking current. To keep below the maximum of the pin you should use a value of :-
3.3 / 0.006 = 550 ohms
But I would not bother with it as it spoils the noise margin of the input pin. How likely are you to make those three errors all at once?