Find all numbers that are factors of one array and factor into the second array, then print their count
Redundant calculations
You calculate mult1 * mult2 three times. Instead, do this once, assign it to a variable, and use that.

Since you want to never want to calculate when a value is 0, you can set the start of range to 1.
range(1, 101) # 1 -&gt; 100, since (inclusive, exclusive)

Now you can remove that (product != 0) check.
Type hints
At first, it looks like the function accepts two integers. In reality, it accepts two tuples of integers. Consider doing the following:
from typing import Tuple

def get_total_x(input_factors: Tuple[int], test_numbers: Tuple[int]) -&gt; int:

This makes it clear that you want tuples of integers as parameters, instead of a single integer.
Using sets
You use a set, but you don't actually use the set. You're trying to add values to the set that aren't already there, or that you can add to the set. Instead of having that list comprehension, simply cast fact into a set. Does the exact same thing.
fact = set(fact)

Magic numbers
What is the significance of 100? I see in your question you explain, but not in the code. I would assign this to a variable to make it more clear.