filling out quote spreadsheet

Google spreadsheets are not able to be updated when they are embedded into an external page like that. Even if they were, you can’t just create a new one for every request that comes through. If you want to use Google service,s a Google form is a much better idea. This will let you save the responses to a spreadsheet if you wish. You’d need to ask Google support for more information about that.

Apart from that there’s many form builders available for WordPress, so they would be my main suggestion.

We are using this as a quote. We need to be able to export those information into excel/google sheet with our letter head information and add the quote prices and send it back to the customer in pdf form. Is that possible?

It may be possible depending on the forms package. Some will work with that and some won’t. You’ll need to look at what’s available to see what suits your needs.

At worst you can always find a forms plugin that has action hooks available that let you create PDF’s from the form values.

As well as the free ones on here there’s also a whole lot of commercial products that might do more of what you are looking for, so look around and see what suits you.