Is space in the iCloud included in the subscription to iTunes Match? If so, how much?

No.

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No. iTunes Match does not use iCloud space. Nor does it come with any iCloud space.

iTunes Match has a limit of 25000 songs for songs that were not bought through the iTunes store. If they were purchased through iTunes they do not count toward that limit.

Subscribe to iTunes Match - Apple Support

WIth iTunes match, your music does not use any of the space in your iCloud. It uses its own seprate space with is included in the yearly subscription cost and heals the space for 25,000 songs.