In the poem "The Terminal," what impressions do you form of the boy? How does the poet create sympathy for the boy?

The first question that is being asked is an opinion question.  Answers will be different for different readers.  As the question states, the main job is to provide justification for why you feel the way that you do about the boy. 
One impression that I form about the boy is that he is young.  The poem states that he is four years old.  I have a son exactly that age, so my impressions of the boy are immediately influenced by my own son.  I picture how my son would respond in the environment that the poem describes.  The child and his parents are in a noisy and crowded area.  It says the boy is following the parents.  Knowing my son, I feel that the boy is not only confused but also frightened.  If the boy were excited and happy about being there, he would likely be next to his parents or even leading them.  When my own son is somewhere that he is familiar with, he often runs in front of me out of sheer excitement.  He hangs back when he is scared.  Hiding behind a parent is a natural posture of protection.  
The second stanza further clarifies my impression of the boy.  He is a boy of mixed ethnicity, and his fear escalates and mixes with feelings of isolation as the second stanza continues.  The boy is astute enough to realize that he is not quite like his mom or dad, so not having a queue for him probably increases his feelings of anxiety.  
The poet creates sympathy for the boy by making him so young.  The reader wouldn't feel quite as much pity for the boy if he were 25 years old, but a child naturally provokes readers to want to offer protection.  We feel sorry for the boy and his isolation.  The reason for his isolation also creates further sympathy.  If the boy were shunned because of something that he did, we might not feel as much sympathy, but the boy is isolated for something that he has no control over.  The poet's repetition of "tired and confused" also creates sympathy.  At some point in life, most readers have been tired and confused.  It's not a fun feeling, and knowing that a small child is experiencing that makes the boy a very sympathetic character.