Learn Japanese with Anime - How Many Breads Have You Eaten In Your Life? (JoJo's Bizarre Adventure)

Analysis

お(お)前(まえ) (pronoun) is a rough way of saying “you”. You need to be very careful using this word as it could be friendly or offensive depending on the relationship between you and the listener so it’s better not to use お(お)前(まえ) in real life.

The は particle shows the preceding noun is the topic of the sentence. So お(お)前(まえ)は is like “as for you” or “with regard to you”.

今(いま)ま(ま)で(で) (adverb) ：今(いま) means “now” and ま(ま)で(で) means “until” so 今(いま)ま(ま)で(で) means “until now”, “so far” or “up to this time”.

食(く)っ(っ)た(た) means “ate”. It’s the past tense of the verb 食(く)う(う) meaning “to eat”. 食(く)う(う) (eat) and 食(く)っ(っ)た(た) (ate) are the rough version of 食(た)べ(べ)る(る) and 食(た)べ(べ)た(た) respectively.

So 今(いま)ま(ま)で(で)食(く)っ(っ)た(た) means “ate until now” and it modifies the following noun パ(パ)ン(ン) meaning “bread”, so 今(いま)ま(ま)で(で)食(く)っ(っ)た(た)パ(パ)ン(ン) means “bread (that) you ate until now”.

The の particle is used when the preceding noun modifies the following noun. And the following noun is 枚(まい)数(すう) meaning “the number” so パ(パ)ン(ン)の枚(まい)数(すう) means “the number of breads”.

枚(まい)数(すう) consists of the counter 枚(まい) and 数(すう) meaning “number”. The counter 枚(まい) is only used to count flat shaped objects such as paper, tissue, plates, towels, and so on. In this case, he refers to slices of white bread which is flat so the counter 枚(まい) is used. So パ(パ)ン(ン)の枚(まい)数(すう) actually means “the number of sliced breads”.

を is the particle that indicates the direct object of the following verb.
The direct object is 今(いま)ま(ま)で(で)食(く)っ(っ)た(た)パ(パ)ン(ン)の枚(まい)数(すう) meaning “the number of breads you ate until now” and the following verb is 覚(おぼ)え(え)て(て)いる meaning “remember”.

Lastly, のか (particles) marked by rising intonation is used to ask a question about what you see or hear. In this scene, he was asked how many lives he has taken, which leads him to ask back this question.

So お(お)前(まえ)は今(いま)ま(ま)で(で)食(く)っ(っ)た(た)パ(パ)ン(ン)の枚(まい)数(すう)を覚(おぼ)え(え)て(て)いるのか means “Do you remember the number of breads you ate until now?”

What he’s saying is you never count how many slices of bread you eat because they are only common food which is not important enough for you to keep track. And for Dio who is a vampire, people’s lives are his common food, just like bread for normal people.