How much difference will one link make?

I have a do-follow link from Reuters.com to a finance niche article. Is it more beneficial than a few smaller sites than Reuters.com in terms of ranking my article?

When you do-follow, it is more beneficial to Reuters than to your site. Have you tried linking articles within your website instead?

I think the op means they have a link from routers pointing to their website.

If that’s the case, and it’s do follow it’s say it’s extremely beneficial.

It is good that you get link from the Reuters, share it via social media channels to get more exposure.

If you use the old pagerank as the guiding metric - when you have the choice of 10 PR2 backlinks and 1 PR6 backlink - I'd go for the 1 PR6 (reuters) backlink anytime over the 10 or even 20 PR2 backlinks.
Apparently, google seems to favor extremely high PR backlinks off late, as they know these pages are very hard to be abused, etc, so having 1 very high PR backlink is worth so much more and would benefit so much more in terms of your site's authority as well.

Reuters.com is a huge site. And a link pointing from it should help you a ton with your ranking.

Especially considering the link is relevant.