Sylas' Skill Max Order: W → Q → E
R Steal: 200% of the stolen ultimate CD
Level 1: If Sylas uses Q on you, vault him because you will avoid the explosion after 0.6 seconds. You hard win level 1, so play aggressive. His Q comes up 2 seconds before your E does.
Level 2: Sylas will likely level up his E, which isn't a problem because Quinn E can cancel Sylas dash from his E.
Level 3: Sylas will engage with his E on you, and so you will save your E to disengage from his E in this matchup. When you do this, Sylas will launch his Q, but use your Harrier proc to out run his Q explosion. When his combo is down, re-engage on him because he's useless after that.
Level 6+: Sylas will steal your R to come back to lane, so if you anticipate him backing, don't let him get your R. Most Sylas players don't know how Quinn R works or that it's a channel, so I have seen a lot of Sylas players int with Quinn R.
First, Sylas Q is 775 range, while your auto range is 525, so he has the range advantage with his Q poke. Be mindful of this because his Q detonates after at the end, which does additional damage, so try not to be at the end of his shackles when he uses this ability.
In this lane, SAVE YOUR VAULT ALWAYS! Let Sylas use his Chain E on you, and when he dashes towards you, use vault to RETALIATE and push you back.
When you vault from his chain pull, you can indefinitely kite him since his gap closer is gone.
The matchup is pretty easy so long as you don't get hit by his Qs in lane, and you vault to retaliate against his engage in lane.
You beat Sylas pretty hard too because he relies on using his R against champs, but him stealing your R means that both of you don't have a combat ultimate. If sylas steals your R, just inform your team that he has it and might plan a roam!
Play aggro in lane. :)