As I said in my comments, "uphill" comes from the martial metaphor, "uphill battle".
The metaphor is that it's much easier to defend the top of a hill, during a battle or military conflict, and much harder to prosecute or attack going the other way, i.e. uphill. Hence the related phrase "seek high ground".
Thus, as an extension of the metaphor, and in combination with the by-now stock term "Generation <Whatever>" (as in Generation X, Generation Y, etc), "Generation Uphill" means that the current generation, also known as Millenials, who are just now coming of age, have an uphill battle in front of them.
As in the status quo (in terms of economy, market structure, political parties in power, and so on) is such that the effort required for them to become successful is meaningfully greater than it was for previous generations to achieve similar levels of success. The common example given is student loan debt, the negative balance one has to pay off before accruing capital for his own purposes, is much greater than in the past. And so on.
Whether or not you find this label or argument convincing is another question worthy of another debate, but that's what's being implied by the label.