Will the entry of a nun into the house affect the family fortune?

This will not affect, but will bring good luck, nuns, they will be protected by Buddhism, that is to say, they are devoted to practice, in order to do their best to all sentient beings in the world, they will generally be protected by gods or earthly branches. It's a good thing to come to your house for alms, and it's to accumulate blessings for you. If the giver becomes a Buddhist in this life, you are supporting a Buddha. Think about it, what a blessing it will be.