Captain reported a fuel spill at the gate. With the aircraft being enveloped in fumes the reporter refused the aircraft.

Narrative

Captain and First Officer checked in with ZZZ gate agents at [the gate]. They were informed of a fuel spill cleanup in progress visible from the terminal window. Additionally; that the flight attendants (F/A) were on board. Both pilots entered the Jet Bridge and detected the odor of jet fuel. The Captain entered the aircraft and found the three F/A's gathered in the rear of the aircraft near the aft galley. He asked if they were aware of the fuel spill and directed them to open the window shades. All three thought that they smelled something but didn't pursue the thought. Captain then directed all three off the aircraft and joined the two pilots on the Jet Bridge where the Jetway door was opened for airflow.The Captain then called Dispatch inquiring if the ops center knew of the spill and operational impact. Coordination with maintenance came next to ventilate the aircraft of vapors. Gate agents came down the Jet Bridge informing the crew of station ops wishing to board passengers within 30 minutes- rebuffed by the Captain. Fire Marshal came on board to assess the condition of the cabin. The dispatch release still required sign off. And it just kept coming. At some point in this series of events the Captain realized his eyes were irritated and burning and nasal passages bothered. He then made the decision to refuse the aircraft due to the tremendous amount of vapor in the rear cabin and galley area and called dispatch. This led to a series of calls to 'pilot push' him into acceptance. Captain attempted to find the refusal code to enter into computer but was unable to find it. With eye burning sensation worsening while again talking with Dispatch; Dispatcher offered to enter the write up. The crew left the Jet Bridge for their respective crew centers. Total exposure lasted approximately 60 minutes. The sense of smell acclimated to the odor and it wasn't until the sensation of eye burning made the crew aware there was a health concern to be addressed. Both pilots reported illness/injury to the crew desk and were removed from the remainder of the trip pairing.