I said this before, but might as well say it again:
Nylander can match himself up to Pastrnak, Ehlers, Monahan, etc. None of those guys got over 6.75 mill per year. Really, he shouldn't be getting much more than Ehlers did (6 mill AAVx 7 years). I personally think the main hold up is that Nylander's agent is probably using cap percentages and sticking hard to the "He did well for two years" thing. Pridham is probably sticking to the hard cap numbers because he does not think the Leafs should have to pay for a major inflation in the cap due to expansion and totally disregarding the fact that he put up two good years instead of one. Monahan put up two good years as well + was in the NHL for an extra half year (Nylander was in the AHL first and then played a half year) + has positional value (he was a center his entire career) + has defensive value. Ehlers signed early but you can bet his agent was banking on his client putting up similar numbers and was not using cap percentages because otherwise his agent just left a significant amount of money on the table. He two likely would have negotiated with the same sort of leverage as Monahan, minus the positional value and defensive value, hence he got a significantly lower cap percentage and overall dollar amount. Really, that is what should be happening to Nylander too.
What I would do, albeit with less knowledge of how much this would benefit the Leafs compared to cap wizard Pridham, is stick to the hard cap and to a 7 or 8 year term, but structure it in a way that would benefit Nylander more financially and give him some peace-of-mind about not getting dealt easily. This would apply to Marner and Matthews as well. The Leafs seem to be willing to sacrifice real money to benefit cap money, so might as well flex the financial muscle you've got.
The first thing to note is that there is a CBA negotiation in 2020-2021. Make that cap number as low as possible, with a signing bonus as high as possible. That way if there is a lockout, he doesn't lose out on much money. Front load his two RFA years (2018-2019 and 2019-2020) with a salary greater than his cap number, but not significantly greater. Maybe 500k-1 mill more than his cap number each year. Then his 2020-2021 salary will be quite low, and really you could make his 2021-2022 salary quite low as well. Then once again load up his UFA years with over-cap money for extra trade protection. By giving him signing bonuses, you are giving his money up front rather than over the course of the year. So the Leafs' provide protection from the lockout and from trades (without having to give him a significant NTC or anything), plus giving him a good portion of money at desirable times (typically the earlier you can get money, the better because of interest). In return, Nylander makes concessions on his cap number and term. Which really also benefits himself as well because that gives the Leafs more cap space to make a better team, which I would think also means something to him as well.
Obviously there must be some piece of information I am missing because if it was this simple, there is no reason why it would not be done unless either party (or both) is really trying to screw the other over (i.e. if Nylander's 8 mill ask is legit or the Leafs are trying to go sub-6). But if we are talking about less than 1 mill difference, the Leafs may decide they take a slightly larger hit financially to ensure they can lock up a key player on less cap.