Yes. There's two ways you could go about it, actually:
1. Because the lead would be clicking on a Marketo-sent email to a Marketo landing page, it will associate any additional form fields filled out with that lead.
2. If you go ahead and include the identifying lead information you have in the form (such as First Name or Email Address) on the Marketo landing page your email links to, you'll see those fields pre-populated.
Note that I'm stressing using Marketo's in-house landing pages rather than taking form code and placing it on an external site.