Kinugawa theme park pass worth it?

I want to visit Edo Wonderland and Hippari Dako in Nikko. I will be departing from Ikebukuro Station early in the morning. I read about the Kinugawa Theme Park Pass and I'm not sure how the round trip would work? Can someone please help? Thank you!

Do you intend to go from Ikebukuro to Tobu Asakusa and then on to Nikko, and then to Kinugawa?

If so, The round trip would take you to and from Nikko or Kinugawa Onsen from Tobu Asakusa. Depending on which train you take, you may have to transfer at Shimo-imaichi or you can go direct to Kinugawa Onsen.

I'm thinking of getting a JR pass and just wanted to know how I could save the most money

Do you mean a JR East Pass or JR 7 Days pass?

Im going to be travelling a lot within japan and im going for 20+ days so i was thinking of getting a 14 day pass

Without knowing your full itinerary, I can't recommend if JR pass will be worth or not. But if you will just be in Tokyo and Nikko, then Kinugawa theme park will be worth it. It wouldn't make sense to spend 28300yen on 7days JR pass instead of just 6000yen on Kinugawa theme park

Kinugawa is not directly accessible by JR trains, so the Kinugawa Themepark pass has the advantage of the Tobu trains combined with a savings of about 1500 yen per person.

I don't know about your full itinerary, but Kinugawa can be done in a side trip from Tokyo so the pass may be still be a good deal even in combination with a JR pass, especially if you can condense all of your other long distance travel into a 7 day pass.

this is my itinerary:
Day 1-7: Tokyo
Day 8: Fuji-Q Highland (sleep in tokyo)
Day 9: Nagoya and head for Kyoto (sleep in kyoto)
Day 10: Kyoto
Day 11: Uji and Nara and head to Mt Koya (sleep in Mt Koya)
Day 12: Osaka(sleep in Osaka)
Day 13: Universal Studios
Day 14: Hiroshima(sleep in Hiroshima)
Day 15: Onomichi for biking (sleep in Hiroshima)
Day 16: Yufuin and then to head to Nagasaki (sleep in Nagasaki)
Day 17: Fukuoka
Day 18: Fukuoka (head back to tokyo overnight)
Day 19-21: Tokyo, then off to the airport

Hmm, looks like you are gonna need a 14 day jr pass anyway and will still have a few extra days that you could use to go to Kinugawa.

Also, I made a mistake in my previous post. I should have said that JR trains to Kinugawa are not fully covered by the JR Pass. There is the special JR Kinugawa limited express trains that run on Tobu lines. You'll need to pay extra to use it with a pass. I'm not sure how much the surcharge is, but its probably only a few hundred yen. So basically if you have a JR Pass you'll save a few hundred yen more than if you buy the Kinugawa Themepark Pass.