Hi Gotgear,
Thanks for contacting Apple Support Communities!
We understand that you're interested in learning more about the size limit of files you can save in iCloud.
iCloud does have a 50GB limit and that the size is not larger than the storage you have available in iCloud. You can learn more about this feature here: Access and manage your files in iCloud Drive
"When you sign in to iCloud, you have access to iCloud Drive. With iCloud Drive, you can keep files and folders up to date across all of your devices, share files and folders with friends, family, or colleagues, and more.
You can store files* in iCloud Drive as long as they're 50GB or less in size and you don't exceed your iCloud storage limit. If you need more iCloud storage, you can upgrade to iCloud+. With iCloud+, you can also share iCloud storage with your family, without sharing your files. Learn more about prices in your region."
Take care!