Hi there,
At this time it is not possible to associate Contacts and Deals during a CSV import into Hubspot. You would have to import them separately, and then manually associate them in Hubspot after.
One option is to use API to import the data, so that you can retain the relationships between your records. We offer this as part of our standard data migrations. You can check out how this will work with a free sample here: https://www.import2.com/hubspot/crm
Best,
Ashley