Not really. Nordic languages can be broken into three broad categories of dialects, East Nordic (Swedish), West Nordic (Norwegian/Danish), and Insular Nordic (Icelandic, Faroese). Elfdalian occupies a middle position between East and West (Swedish and Norwegian). In contrast, the literary Old Norse that is preserved and studied is predominantly Insular (Icelandic), with some West Nordic manuscripts thrown in.
There are, evidently, some specific features of Old Norse that are preserved in Elfdalian and not in other North Germanic dialects, but that doesn’t mean it’s especially close to the older language in general. American English, for instance, preserves certain features that have been lost in British English, but that doesn’t mean we Leftpondians sound like Brits from centuries ago. (Nearly every dialect preserves some features that have been lost in its sister-dialects.)
