You can kill him pretty easily up until levels 8 or so, then he will win most engagements.
Poke him with your Q, don't get hit by undertow, don't let him harass you for free. Trade autos when your passive is ready on him. Use your combo once at level 2, then again at 3 and he should be either dead or forced out of lane.
Jarvan has pretty huge burst at level 6 with ignite, make use of that. Harass him a lot at 5, and if he tries to stick around at 60% health you can easily get the kill.
If the Olaf took flash, initiate with your ult and save the E>Q for after he flashes out. --- If you believe in Jesus Christ, have accepted Him as your Lord and Savior, and are 100% proud of it, put this in your sig. g-cube's Vice President of Cakes.
I'm not sure it is possible to beat Olaf as Jman in the top lane if Olaf maxes out 'Q' and harasses Jman all day with flask. It does far too much damage with picking up the axes and if Jarman tries to harass back, he'll take some true damage to the face while Olaf can just lifesteal some of that back. It's tough, but if Jarman gets a gank or two he might be able to take advantage of an early item or two to pressure Olaf into being zoned.
my friend is in plat and he does it all the time. --- "I read this as a Bannanable Offense. I was like, what ksing with Soraka?"-Kirby 1207 http://us.battle.net/d3/en/profile/CommanderKJK-1173/hero/60977
If you Q Olaf when he beelines to you to E and then aa as he E's you, trade won. Get a feel for when you can burst him with R+ignite after landing Q. Make sure to always drop E for extra armor+attack speed in your ult if you haven't dropped it already. --- And all the feeders and trolls will look up and shout "Carry us!" ... and I'll look down and whisper "No"