It's a bit more complicated, actually:
Theia is being developed by TypeFox, Ericsson, RedHat, ARM and more.
Orion is being developed by IBM and more.
Both Theia and Orion are projects under the umbrella of the Eclipse Foundation:
https://projects.eclipse.org/projects/ecd.theia
https://projects.eclipse.org/projects/ecd.orion
The Eclipse Foundation (in the very most cases) does not develop software. They also usually do not pay developers. Their role it to arrange that companies and contributors play fair and nice when creating and using open source software.