Should I continue reviewing a paper after having discovered plagiarised content in it?
Don't bother with more analysis, there is no point, since the paper should be withdrawn or rejected because of the plagiarism (if it isn't decline further review for this journal). Write a brief report along the lines

The manuscript contains 7 pages which are almost verbatim copied from &lt; plagiarized paper >. In view of this I refrain from any further analysis as I expect you to reject the manuscript.

You should also check, whether the paper has already been published as a preprint (e.g. on arXiv) and if so inform the editor and suggest him to require the authors to withdraw from there too (I know of a case where this happened) but you may also contact arXiv directly (to protect your anynomity don't contact the authors or make your knowledge public).