Everywhere you look on the internet it says the house has a 1.4% advantage on an even money passline bet. That means the player is at 98.6%. For every $100 the player puts in action the house is also putting $100 into action. That's a combined wager of $200.
98.6/200 = 49.3%
So the player's chance of winning each individual passline bet is 49.3%