Sarah's poem is built on a simple, stark idea: staying alive and truly living are not the same thing. The title, "survival," sets the tone. Survival suggests getting through something hard, and the poem seems to say that getting through is not the same as thriving.
The speaker splits the two ideas in the last stanza. Living "shows beauty," while being alive "shows pain." The poem doesn't say which line belongs to which, but the order of the opening lines and the title suggest that merely being alive is the painful one. It sounds like someone who is breathing and carrying on, yet not feeling much joy in it.
The mood is quiet and heavy. Short lines and plain words leave a lot of white space, which makes the poem feel bare and a little lonely. The word "pain" sits alone on its own line, so it lands with a thud. There's no escape offered, just an honest, tired observation.