Oregon is definitely not tied with likely voters in the 2018 OR-GOV election....
Sure Gravis is actually hitting many of the right numbers from a polling methodology in terms of age groups, voting history in the 2016 Presidential Election, still their overall Trump Approval/Disapproval numbers look a bit suspect...
It is absolutely true that Kate Brown will perform much more poorly than a Democratic Candidate for US-PRES or OR-SEN (Upstate-Downstate Oregon political dynamics that I have mentioned frequently on other posts).
There are many voters in Downstate Oregon not enamored of her support for Gun Control Legislation that she signed into law, as well as your usual fringe Oregonian Christian Coalition types pissed about support for Female Reproductive Choice that she signed into law, expansion of protection for LGBTQ Oregonians, etc...
We also have the old canard of the "jobs vs environment" bag, etc....
Still, even this Gravis poll shows that the vast majority of "undecided voters" are 18-49 which is a demographic that will be most supportive of her candidacy in a 100% Vote-by-Mail (VbM) and AVR state with extremely high turnout even in Mid-Term elections.
That old Gravis dawg don't hunt and once again is up to some funky business with the numbers and none of them have ever likely set foot in Oregon in their lives....