Mapping one key to multiple commands in vim

Assuming <C-S-F6> actually works (it probably won’t in CLI Vim), you must escape the bar or use <bar> instead:

:nnoremap <C-S-F6> :up \| !pdflatex %:t<CR>
:nnoremap <C-S-F6> :up <bar> !pdflatex %:t<CR>

See :help map_bar.