N'est-ce-pas is pronounced, loosely, "Ness-Say Pah".
Certain lazy French accents, the arizonians of the French accent world, will slur the words together, creating something akin to "Nessuh (smashed into one syllable) pah", but the "ce" is still audible compared to "N'est pas", which would be pronounced "Nay Pah", the "s" and the "t" both being silent by english definitions of pronunciation.
It isn't silent.
N'est-ce-pas is pronounced, loosely, "Ness-Say Pah".
Certain lazy French accents, the arizonians of the French accent world, will slur the words together, creating something akin to "Nessuh (smashed into one syllable) pah", but the "ce" is still audible compared to "N'est pas", which would be pronounced "Nay Pah", the "s" and the "t" both being silent by english definitions of pronunciation.