2nd generation refers to pups born from a Maltipoo to Maltipoo mating as opposed to 1st generation in which a toy Poodle is paired with a Maltese.
1st generation dogs will hold traits from both Poodle and Maltese breed, however 2nd (and 3rd, 4th and so on) generation Maltipoo are pulling more traits from his/her Maltipoo parents. Genetics go at least 5 generations back, therefore a 2nd generation Maltipoo will have one generation of Maltipoo traits and four possible traits brought in by 4 generations back (grandparents, great-grandparents, and so on).
With this said, it is true that traits held by the dam and sire will have the most affect in regard to eye coloring (and this holds true for coat color
Most, but not all, Poodles have dark eyes. The standard calls out for 'dark eyes'. The actual color will vary from amber to dark amber… almond to black. The Maltese standard calls out for 'very dark' eyes. While black eyes are preferred, many Maltese have lighter eyes ranging from amber to dark chocolate brown. Very few have blue eyes, as it simply is not a trait of this breed.
There are some Poodles with blue eyes, though this is rare since it is related to the merle color which is being bred out of the breed as it has been linked to health problems. Note that Merle itself does not cause health issues; however, it is when merle to merle is bred that issues often arise. And since a dog can have 'hidden' merle genes, breeding merles is not recommended.
Looking the aforementioned colors that are possible, we can know that most Maltipoos will have dark eyes, ranging from amber to black, once that change takes place and eyes darken on a newborn puppy.
The few blue eyed Maltipoos that exist most likely have a merle Poodle somewhere in the bloodline - and most often within those 5 generations back that have the most influence on the traits that a puppy will inherit. There are a few exceptions such as a Maltipoo with hazel or very light brown eyes; but this is very rare since both Maltese and Poodles generally have dark eyes.