I'd say inconclusive
Jason's Regenerationn makes him extremely difficult to put down, he's regenerated from having
massive chunks and limbs blown off his body in seconds, and his tolerance for pain makes him nigh impossible to slow down
However, the Demogorgan's own regen is impressive, and though it is less potent than Jason's, he can escape into the Upside Down to heal if he needs (though the portal creation process does appear to take some time)
Their durability and AP appear to be even, though Jason can amp himself via rage, so he could potentially gain an edge.
Experience is tough to call. The Demogorgan has presumably been hunting around the Upside Down for awhile, and has taken down an entire group of trained government agents all by itself. Jason, however, has solo'd groups of trained soldiers and mercenaries who had knowledge on him, outsmarted a small team of government agents, fought Freddy Kreuger and Leatherface to a standstill, and even taken on Ash Williams and a group of horror movie survivors. So I'd say Jason takes it in combat experience and for fighting opponents equal to or greater than himself.
Intelligence goes to Jason easily. He already smart enough to set up traps for groups of people, and with his intelligence boost he gets from Freddy, he was easily able to recognize, understand and counter a trap set up for him by government agents. The Demogorgon is animalistic in mindset, and easily fell for a trap set up for it by Nancy and Jonathan.
Their abilities kinda counter each other.
Demogorgons. His electricity manipulation is useless for combat, and I don't remember it using telekinesis in battle (it only used it to open a lock iirc). Portal Creation is useful for escape, but it takes time to get going. However, his enhanced sense can probably counter Jason's stealth and illusions (Jason can only make himself appear as a little boy to my knowledge).
Jason has teleportation to easily gain an edge, and can use it to run away if he needs to (he is willing to run if his opponent outnumber or overpower him). Shift allows him to disappear from the area and quickly traverse it, making him completely undetectable.
Calling on the Mind Flayer is outside help, so that's a no go, and Jason has resistance to mind manipulation.
Don't think it's fair to compare a blow from a spiked bat from Steve (a normal human) to a blow/slash from Jason. Jason is blatantly superhuman, and has casually punched through steel and humans wearing body armor
However, Demogorgans ability to escape into the Upside Down and regen makes him hard to put down, and Jason's insane regen and teleportation make him hard to put down. So really it ends up with them beating the hell out of each other for days on end.