Your partner will have to file a gift tax return to report the gift. No gift tax will have to be paid unless your partner has made total lifetime gifts of more than $11.5 million, but the gift tax return has to be filed. The gift will reduce your partner's lifetime gift and estate tax exclusion.
You cannot file a gift tax return with TurboTax. It would be best to go to a tax professional.
You, as the recipient of the gift, do not have to report it or pay tax on it. You do not enter it on your income tax return.
You will be a half owner of the house, but you alone will be legally responsible for the entire mortgage. There might not be any problem with that, but I suggest that you consult a lawyer to make sure. You should initially meet with the lawyer alone, without your partner.
