Yes. Eva reuses a label or folder you already have when its name matches one in her label list.
How to make Eva use your existing labels
In Eva's chat, click the gear icon, then Abilities.
Under Labels, add your existing label with exactly the same name. Capital letters don't matter.
From then on, Eva files matching email under your label instead of creating a new one.
Good to know
Eva only applies labels from her list. She never removes your own labels.
In Outlook, this works with categories and with folders at the top level of your mailbox. With IMAP, it works with your folders.
Don't rename your labels to match Eva's, for example "1. Notifications": that only creates a second label.