Hello awesome person,
You won't be able to migrate an existing Umbraco 7 project to Umbraco Cloud. If you wish to host your v7 project on Umbraco Cloud, then you'll need to upgrade it to v8 first. These are the official statements.
However, since Umbraco 9 has been released recently, I would recommend either to have the project re-build from scratch in the new version of Umbraco, or to be upgraded from 7->8, and then from 8->9.
A bit about myself:
My name is Ion, and I love helping customers like you to succeed in their online presence. I have over 6 years of experience with Umbraco, and I am an Umbraco certified Master. ( I have attended all of the Umbraco official training courses, including the Umbraco Cloud training course) That gave me the opportunity to learn the best practices while building a fully functional website.
I'd be happy to have a chat about the workflow and future of the project. If you have not found anyone yet, let's connect.