How close is English to Pali?
You can find this info on the wikipedia page for Indo-European Languages in the form of a family tree below, with Pali and English highlighted with a yellow box.
Legend:

Green: Language still in use
Red: Language extinct
White: Categories

English is a Germanic language, while Pali is an Indo-Iranian language. Both come under the major family of Indo-European languages.

Credits: Modified from this image