For short hand: the horizontal line is $H$, the center vertical is $C$, the one to the left of $C$ is $L$, and the one to the right of $C$ is $R$. The cells are:
\begin{array}{|c|c|}
\hline
1 & 2 & 3 & 4 \\
\hline
8 & 7 & 6 & 5 \\
\hline
\end{array}
Fold $H$ last: 4 ways
$H$ and $L$ have 1 way to fold, so here can be ignored. As $C$ and $R$ have 2 ways to fold and their order doesn't matter (make dulplicate orientations) there are only $2\times2=4$ different ways to fold the sheet ignoring $H$ for the end.
Fold $H$ first: 7 ways
If one were to fold $H$ first, there are 6 different ways to fold the sheet. 4 are simply folding $R$ and $C$ in their 2 possible ways. The other 2 involve tucking cells $3-6$ between $1$ and $8$.
The seventh was well decribed by klm123 and aschepler: Fold $Ho$ . Slide $4-5$ between $1,8$. Making it more like a cylinder than a triangle, continue sliding in until $4-5$ are between $2,7$ and $3,6$ are between $1,8$. Then you can fully flatten the LoCoRo creases, making it a 1x1 square.
Fold $R$ then $H$ first: 6 ways
If one folds $R$ then $H$ one gets 6 orientations in exactly the same way as the first 6 option from folding $H$ first.
Fold $R$ and $C$ then $H$ first: + 4 ways
Neither $H$ last nor $L$ last scenereos can cover square $1$ as long as $H$ and $L$ are both folded out and no tucking possible as the first two folds quickly shorten the paper. This means that there are 8 possibilitys: $RoCoHoLo,RiCoHoLo,RoCiHoLo,RiCiHoLo$ and the same ones with $LoHo$ (but these 4 are duplicates of $H$ last).
Fold $R$ and $L$ then $H$ first: see below (Fold $L$ and $R$ then $H$ then $C$)
Fold $C$ then $H$ first: 3 ways
$C$ can now only be folded "out" in the same direction as $H$ or cell $1$ is covered.
Once this is done, however, $R$ can be folded into three different orientations. The options are to place $4$ and $5$ between $1$ and $8$,$2$ and $3$ or $7$ and $6$. Folding $L$ makes it a 1x1 but doesn't change the number of patterns.
Fold $C$ and $L$ then $H$ first: 3 ways
$C$ can now only be folded "in" and $L$ must be folded "out".
Similar to the previous case, there are 3 different options based on folding $R$ after $H$. They are to place to place $4$ and $5$ at the bottom, between $6$ and $7$ or between $2$ and $3$.
Fold $C$ and $R$ then $H$ first: see above (Fold $R$ and $C$ then $H$ first)
Fold $L$ then $H$ first: 7 ways
$L$ can now only be folded "out" and $H$ must be folded "out".
This yields 7 different possibilities based on where $3-6$ are placed. There is: one with $4-5$ between $2$ and $7$; 2 ($Ri$ and $Ro$) with $3-6$ between $1$ and $2$; 2 with $3-6$ between $7$ and $8$; and 2 with $3-6$ on the bottom.
Fold $L$ and $R$ then $H$ then $C$: 6 ways
$L$ can now only be folded "out".
This yields 6 different possibilities based on where $3-6$ are placed. There are: 2 ($Ri$ and $Ro$) with $3-6$ between $1$ and $2$; 2 with $3-6$ between $7$ and $8$; and 2 with $3-6$ on the bottom.