Is it possible to assign many pins to one variable?

there is no such things as assigning a pin to a variable.

there is no magic happening, if you want int x; to take the value of the pin Digital 3 then you need to do x = digitalRead(3); (of course better if you gave that pin a name before).

const byte motorPin = 3;
int motorState;
...

motorState = digitalRead(motorPin);

if you need another variable to be the same as motorState, then do

const byte motorPin = 3;
int motorState, anotherState;
...

motorState = digitalRead(motorPin);
anotherState = motorState;

and you don't send signal to a variable, you set PINS to a specific value.
motorState = HIGH; won't make pin 3 HIGH (just the variable) but

 motorState = HIGH;
digitalWrite(motorPin, motorState);

will set that PIN high (and the variable)

makes sense?