Can we use the same G Suite account for several domains we have? What about the aliases?
We don’t know about any limit with the domains, we are also using several ones.
Important is the difference between the aliases and the additional domains. An alias will only be stored in G Suite and is active for all users (so I could also receive a mail via email@example.com (mailto:firstname.lastname@example.org, e.g.) as seibert.biz is an alias for us.
Domains that are being stored as additional domains, become independent users and the users that have been assigned to that domain, have to login with that one. So, a user can not be in two domains with a non-alias domain, but needs an additional user.
Please find more about G Suite in general on this page.