Mr Walsh, on a visit to Ulster University in Belfast, said: "Without question, it will be an advantage."
He would prefer that the UK abolishes Air Passenger Duty (APD).
But, in its absence, he said carriers within his International Airlines Group (IAG) would "certainly look at what is on offer" from Stormont.
Economy Minister Jonathan Bell has promised a decision on an air route development fund by the end of next month.
Potentially, it could be a Â£4m incentive package to help fund important business and tourism connections.
The Northern Ireland Executive could, on its own, scrap all APD, but it would cost it at least Â£55m to repay the Treasury in lost tax revenue.
Mr Walsh - a long-standing critic of APD - said it was "unfair to ask Stormont to make up the gap", adding "the chancellor should pay for it."
He also expressed potential interest in Bombardier's new C-Series aircraft, which has struggled for orders and put the company under huge financial strain.
He said the smaller version - the CS100 - "is possibly an option" for his airlines operating at London City Airport.
"People will watch its introduction into service (later this year)," he said.
"If it can demonstrate it is not just a good aircraft on paper then it will get more interest."
A Stormont fund to attract new air routes has the backing of Willie Walsh, the boss of British Airways and Aer Lingus.