What did Yosef see in the chief baker's dream that prompted him to give a dire interpretation?
Targum Yonasan: The three baskets represented the three ways in which Yisrael were destined to slave in Egypt ("with cement, with bricks and with all kinds of work in the field" (Shemos 1:14)). 1
Hadar Zekenim (to 40:10): The three baskets represented three exiles that Yisrael were destined to suffer, and the top basket, with all foods of Pharaoh, is the last exile, which contains all kinds of exile.
Oznayim la'Torah: The fact that the birds ate Pharaoh's bread did not bode well for the chief baker, since in real life that would have spelled the death-sentence. 3 Moreover, the bread was placed in cheap wickerwork baskets, on his head where he was unable to keep an eye on it and where the top basket was uncovered, allowing easy access to the birds. 4
This also explains why he bluntly foretold his death without any sorrow or words of comfort or apology. (PF)
By the same token, in the chief butler's dream, the fact that he ended up pouring out the wine into the king's cup spoke for itself.
Oznayim la'Torah: As opposed to the butler, who dreamt that he was holding the king's cup, and in his hand; sure signs that all would be well. See Oznayim la'Torah.
Rashi (to 40:13) writes that "Yisa Pharaoh Es Roshecha" regarding the butler means to count him (among his servants). What does "Yisa Pharaoh Es Roshecha me'Alecha" mean here?
Rashbam and Targum Yonasan: It means literally that Pharaoh will decapitate him.