How should (s)he approach the decision?By looking into one's heart, and deciding what one really wants out of life.
Financial constraints are one thing. But one really shouldn't sacrifice truly important life goals (like having children; or even moving to the same city to be with one's partner) for the sake of this industry's (really quite shallow and ego-aggrandizing) "meritocratic" standards. Or even weigh them on the same scale.
To put it another way: By all means, don't give up your creative and intellectual goals -- and don't foolishly neglect your baseline financial goals, either. But really, just screw this idea of "achieving a senior title", or "becoming an industry leader", or any of that stuff.
I mean, these things OK if they come as the result and after-effect of creative and productive work. But the moment one starts to think "Wait, should I have kids with this wonderful person like I've always been dreaming of, or... should I keep plugging away in the hopes being... recognized and chattered about in major media outlets" -- I'd suggest that that's not only where one starts to lose perspective on what's really important in life; one also starts to lose perspective on what it really means to be genuinely creative and successful (by personal, or any other standards) in the first place.
Which after all comes down to: throwing caution to the wind, and putting all your energies into what you think is important and meaningful - and not what other people think is important. (And certainly not what journalists in the business media think is important).
Should a really ambitious person seriously consider not having children at all?
I would put it this way: decide what your ambitions really are, and act accordingly.
If having kinds happens to fall into the space of "ambitions" for you - that's great. If not, that's fine also.
But the "should I have kids or follow my ambitions?" line of analysis seems like a mental trap.