Using %%itikz with \input{fig.tex} to include a LaTeX tikzpicture in Jupyter?

I’ve recently started using JuPyter notebooks and wish to include content developed in LaTeX. I’ve worked out that a code cell with %%itikz can allow me to import a (stand-alone) tikzpicture using \include{fit.tex}. I’ve seen that itikz allows me to specify the LaTeX packages and tikz libraries I need for my figure.
I have two issues:

  1. The packages I specify are already called in the notebook preamble. It would be good if the %%itikz cell could see those so I do not have to specify again.
  2. The tikzpicture is made very small, and my changes to the scaling in the .tex and using --scale have had no effect. It seems that I am inserting a whole page into Jupyter, mostly of white space, complete with page number 1 at the bottom. Use of \input instead of \include has caused errors:
    ! Undefined control sequence.
    \usetikzlibrary
    l.3 \usetikzlibrary
    {arrows,}
    ?
    ! Emergency stop.
    \usetikzlibrary
    l.3 \usetikzlibrary
    {arrows,}
    ! ==> Fatal error occurred, no output PDF file produced!

Is there some way that I can enlarge the figure without having to remodel the source code? Perhaps the input/include approach is not appropriate?