I am subscribed to Itunes match

Is your phone signed into the Apple ID you used to subscribe to iTunes Match in Settings>iTunes & App Stores?

This happened to me on my iPad 2 on iOS 7. I logged out then back in but it did not work...

You might need to start over by opening iTunes on your computer, going to Store>Turn Off iTunes Match, then after a couple of minutes, go to Store>Turn On iTunes Match, click Add this computer, then allow the match process to finish. Then go back to your iPad and try turning on iTunes Match again.

Oh! It's worked now! THANKSSSS I SPENT DAYS DOING THAT!

You're welcome.

Wait, in iTunes Match does all your music back up into icloud?

Yes. iTunes Match will scan your iTunes library, then check to see which songs are already in the iTunes store and upload the rest. Then they are all availble to play and download from iCloud.

It's still not a good idea to delete you music from iTunes once you have iTunes Match because the match process isn't always perfect. You may find that some of your "matched" songs aren't identical to your originals. (A common complaint, for example, is that a song with an explicit rating will be match to the non-explicit version.)

If I brought more icloud storage would I be able to upload more songs?

No, iTunes Match doesn't use your personal iCloud storage. Your annual subscription pays for separate storage for your Match library, which is limited to 25,000 songs, not including songs purchased from the iTunes store.