I'm guessing SHE is living there. It's the time of year when female squirrels give birth. If they are between the floors it may be hard to get her out, particularly if she has given birth. Don't close off the hole until they are gone which could be April +/-. If they die in there the smell will be worse than the animals. You can try trapping her by placing a trap near the soffit opening. (I use Havahart traps - available lots of places and pecan pieces as bait.) Again, if she has babies I doubt she will go in the trap and the babies will likely die inside if she is caught. Tough spot to have them living but they look for out of the way places for this reason.
Can you get in between the floors? Is there an opening besides the soffit or cutting into the ceiling? If so, you could try putting a strobe light inside to flush her out. I use strobes most of the time now. The flashing light hurts their eyes. Used one recently to flush an opossum with babies out of a storage shed. Lots of things to consider. In situations like this I tell people sometimes the best thing is to live with them until the babies start going outside. When they are out during the day is the time to seal the soffit hole. If you seal the hole and she does have babies inside she will tear the soffit apart to get to them.
It's always good to walk around your house every couple of weeks to look for gnaw marks, holes or termites. Might be best to call someone who gets animals out of homes. They may know of other techniques. Hope this helps. I get my strobes off Amazon. $25 +/-.