can I run a filemaker pro database in iCloud

No. This requires website hosting which iCloud does not provide.

Though its true you can host a Filemaker Pro database on iCloud, I did something which might be interesting or valuable to you.

I made a database with all file containers stored outside the database. The result is a lightweight database that links all images/pdf/etc to a path in the same context as the database is stored.

I used then Dropbox and I can access the database from multiple machines, though not edit/add information at the same time. Its even posible to open the database on your iOS device and see changes, etc, with the last stored database on Dropbox.

I know this wont work for anybody, but it did for my girlfriend who stores data at work, and later review it at home.