No, you cannot import all product fields from SI. While the CSV file with product details downloaded from SI has several fields, the custom fields from SI and those listed below are not supported on Cloud.
URL
Images
Accounting item name
Tags
Order UOM or Units
Dispersion
Bulk Wire
Start or End Terminal
Input and Output Terminals, Signals, Labels
Summarize
Approved
Show in product detail report
For up-to-date information about the fields that can be imported to Cloud, always refer to the sample CSV file available in the Import products workflow on Cloud.
Check out this article for more details about importing products from SI.