Is Xerox a verb

Xerox is not a verb and the Xerox Corporation actively discourages its use in that way.

Xerox is a trade mark and a shortened form of the company name, Xerox Corporation. Its use as a generic term for all copying machines is part of a general process whereby proper names are transformed into common nouns, sometimes losing their capital letters in the process. This has been going on for a long time (e.g. "shylock"), and is often applied to modern era trademarks. Similar cases are "coke" and "kleenex," both of which are beginning to be found in formal prose.

Some people also use 'xerox' informally in place of the verb "to copy" or "to photocopy." This is an example of a linguistic process sometimes called "zero derivation," whereby one part of speech is converted into another without some kind of ending. English has done this sort of thing frequently in the past few centuries--e.g. "watch" or "kill" in some meanings. A more recent example of this applied to a trademark is "google." When such usages fill a gap, they are likely to become acceptable in formal prose at some point.