Going from the information we've been given so far, I'm inclined to say yes, but with limitations. The demons are described by those that can see energy as a vortex in which the energy flows, almost like they're a black hole. I could be interpreting it incorrectly, but that could mean they "suck up" the available energy in the area, so the limiting factors become:
How much energy is in the area?
Do other nearby demons share that energy draw and can they disrupt each other?
Is there a defined rate at which they can draw that energy?
How quickly is that energy replenished by the universe?
Can the demons store that energy? If so, do the demons have a maximum capacity?
Do they have a maximum throughput?
If Eve doesn't have a limit on how many links she can create and manage, then she could conceivably draw life from billions of people and large animals. That's if she could form links all at once at any rate. The time it would it take to get blood, drink it, and maintain a link would likely put the maximum number of links in the few hundred thousand.
There are other questions to consider as well since there's an obvious multiverse story arc that should come into play at some point:
We've seen character move between realities (The demons using the in-roads, Gwen and her brother crossing realms, etc), are there some realities where a character will be powerless? We know in the Gwen-verse that magic doesn't exist in her original world, so would a demon going there be just another person?
If Eve were to move between realities, I would expect her blood links to be severed and her to be running on her own life force until you she can form new links, but are there some realities where she couldn't form links since magic doesn't exist or works differently?
How much energy is in the area?
Do other nearby demons share that energy draw and can they disrupt each other?
Is there a defined rate at which they can draw that energy?
How quickly is that energy replenished by the universe?
Can the demons store that energy? If so, do the demons have a maximum capacity?
Do they have a maximum throughput?
If Eve doesn't have a limit on how many links she can create and manage, then she could conceivably draw life from billions of people and large animals. That's if she could form links all at once at any rate. The time it would it take to get blood, drink it, and maintain a link would likely put the maximum number of links in the few hundred thousand.
There are other questions to consider as well since there's an obvious multiverse story arc that should come into play at some point:
We've seen character move between realities (The demons using the in-roads, Gwen and her brother crossing realms, etc), are there some realities where a character will be powerless? We know in the Gwen-verse that magic doesn't exist in her original world, so would a demon going there be just another person?
If Eve were to move between realities, I would expect her blood links to be severed and her to be running on her own life force until you she can form new links, but are there some realities where she couldn't form links since magic doesn't exist or works differently?