Layout 2. (with minor changes)
Reason being, user would be promoted to this screen if they want to register / got the invite link / or whatever the user flow is, but the purpose of this screen is to let user know about the actions which they can choose from, which are going, bail, maybe, & invite, which in this layout are clearly visible to user and action could be taken accordingly.
The minor changes could be:
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Assuming that the image icons (below text 3 going , 1 not) are of users who have opted for going, maybe you can Allign then on top of each other (first on top or last on top), if its something else it's OK to keep it this way.
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Add some lines (not more than 3) below event details such as the topic name or maybe description to let users know what the event is about.
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You haven't used the green color in layout 2, maybe it's because it's just the wireframe try adding the color and see how it looks.
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Use only 3 actions in the top, exclude invite from there, ( you will need more research for that, get some insights & then only apply this one), but generally I haven't seen a lot of users invite if they're themselves a attendee. So maybe you can use it as a secondary action.