Making my cat stop scratching furnitures

I can only add a couple of comments to gjblooms excellent answer:

1. Put the scratching board as close as possible to the place where your cat usually scratches.

2. Don't just scare him away from the places he is not allowed to scratch, try encouraging him to scratch the scratching board.

3. Once he gets used to scratching the board, gradually move it to another location.

4. From my experience, it is easier to prevent a cat from developing the habit of scratching furniture, than it is to train them not to do it.

Gr8 answers above, I'll add one tip:

Cats scratch on tight/firm surfaces, such as a sofa's stretched cloth or wood. Spread LOOSELY any large cloth (a table cloth or a bed sheet would do) on his/her favorite scratching spot, and it will spoil his/her fun. Leave it there for a month or so, until the cat is used to fulfilling his/her scratching needs somewhere legal. Yes, it might not be the most decorative livingroom ever, but it works :-)

We have tried EVERYTHING and I mean everything. We are at our wits end. We have tried the spray bottle, the Soft Paws, scratching posts, kitty condo, catnip, and literally the list goes on! He does it out of sheer joy of watching us get upset and frustrated. Some cats are just stuck in their ways and do it for attention. They realize that when you react to their misbehavior they see that attention you are giving them and feel that is what they need to do to get that reaction out of you. You are not in this boat alone. Hopefully things improve and just think if you find a miracle that stops your cat's behavior then be thankful... it could be worse... you could have exhaused every alternative to declawing and still be in the dark like me. Let me know if you find this "miracle"! Good Luck!

Since he just got there as a kitten, you've still plenty of time to properly train him. If he's a bit set in his ways, well, you've just got to become robotic about reinforcing him.

As others have suggested, placing scratching posts strategically near wherever he's been scratching is smart. However, do know that once they scratch a scent is left (from those claws) and further scratching reinforces that scent (territory marking). Hence, you need to remove that scent by washing it or spraying it with one of those many products you can find while wandering pet stores. Can't think of one in particular, but you must remove that scent to prevent future scratching desires.

In the interim, whatever you decide to do, consider adding transparent  tape over the material/furniture (provided it doesn't damage it too much upon removal; test it obviously). To further convince your kitty, remember that being CAUGHT spraying it with a water bottle will only train him to stop whatever he's doing when you're around. For this purpose, I, personally, prefer to wet my hands and sprinkle my cat when she's not looking by flicking my fingers in her general direction. 

Oh, and keeping your kitten's nails trimmed is good as it'll reduce and scratching damage as well as get it used to getting its nails trimmed. Good luck! 

Double-sided tape does wonders!  Put it on the parts of the furniture where your cat scratches most.  They hate the sticky feel of the tape.  Of course, make sure he has an appropriate place to scratch like a scratching post.  And sprinkle some Catnip on it so that your cat is attracted to the post.