For a striker, yes to some considerable extent. Obviously there's more to it than that, but Kane contributes a lot to Spurs even when he doesn't score: his all-round game is really good.
No it's not mate. Maybe for similar type of strikers, but not strikers who are very different qualitatively, and especially not for strikers who are in different stages of their progression. I really like Kane FWIW, and I'm not going to take sides here since it's still a bit too early to tell either way. However, Martial played mostly as a winger for Monaco behind the likes of Berbatov, similar to how Thierry Henry started out for the team.
His game was (and still kind of is) based on dribbling and creating space for the primary striker, and it's only at United where he has become kind of a focal point of our attack. And even now, he's been shifted out wide on more than one occasion, as opposed to Kane who has been playing as the target striker for a while. Plus, Martial started only a handful of games for Monaco. Granted, Kane did so too at the beginning of his career, but he has been a mainstay for a while, unlike Martial.
So using goals as a metric and extrapolating that to discern their talent level as strikers is misleading, unless they play in similar systems, and are fulfilling similar roles, and you should know that.
PS: This might sound stupid, and counterproductive to a lot Kane's hold up qualities, but I'd like to see him play the Thomas Müller role. Dunno why, but their at times awkward style of play, and their cerebral approach in attack seems kinda similar. This isn't to say Kane is as versatile, or as good of a passer, or dribbler in confined spaces as someone who will go down as one of the modern greats. But given Kane's skillset, he could play as the #10/ #8 hybrid like Müller does so effectively.